Menu
▾
▴
gimp-print-devel
|
From: Marko M. <mar...@gm...> - 2008-08-08 00:37:56
|
Hello list, I have an Epson R280 printer loaded with MIS K4 inks (3rd party substitute for Ultrachrome K3 inks), without LK and LLK, of course. I am trying to figure out the best way to profile it. I will probably use ArgyllCMS for profile generation. If these inks were standard on this printer, I would treat it is RGB printer and print patches using "Uncorrected" mode, but that is not the case. I am thus looking for advice on general approach, so I don't go barking up too many wrong trees. I imagine I need to do this: - Print a gradient for each of the 6 inks using "Raw" option to figure out ink limits for individual channels and where is the crossover between photo and regular inks. Also print combined inks to figure out total ink limit. - Tell Gutenprint about these limits, ideally without recompiling (simply change settings in driver? modify PPDs or /usr/share/gutenprint/5.2/xml/escp2/media/something.xml maybe) - Linearize - not exactly sure how. I see Gutenprint has some HSL curves in media/something.xml - I assume this is the famed "linearization"? I don't see how to linearize individual inks or combinations of inks (M+LM) other then some gamma settings. Alternatively, print unlinearized with "Density" option and let the profiling software sort it out (I'm working in 16-bit). Any hints appreciated. Marko |
|
From: Robert K. <rl...@al...> - 2008-08-08 01:13:12
|
Marko Milisavljevic wrote: > Hello list, > > I have an Epson R280 printer loaded with MIS K4 inks (3rd party > substitute for Ultrachrome K3 inks), without LK and LLK, of course. I > am trying to figure out the best way to profile it. I will probably > use ArgyllCMS for profile generation. > > If these inks were standard on this printer, I would treat it is RGB > printer and print patches using "Uncorrected" mode, but that is not > the case. I am thus looking for advice on general approach, so I don't > go barking up too many wrong trees. I imagine I need to do this: > - Print a gradient for each of the 6 inks using "Raw" option to figure > out ink limits for individual channels and where is the crossover > between photo and regular inks. Also print combined inks to figure out > total ink limit. > - Tell Gutenprint about these limits, ideally without recompiling > (simply change settings in driver? modify PPDs or > /usr/share/gutenprint/5.2/xml/escp2/media/something.xml maybe) > - Linearize - not exactly sure how. I see Gutenprint has some HSL > curves in media/something.xml - I assume this is the famed > "linearization"? I don't see how to linearize individual inks or > combinations of inks (M+LM) other then some gamma settings. > Alternatively, print unlinearized with "Density" option and let the > profiling software sort it out (I'm working in 16-bit). So this printer is essentially a CcMmYK printer, correct? One option you might start with -- you'll need the latest CVS to do this -- would be to copy the appropriate data file from escp2/inks and change escp2/model/model_81.xml to point to the new file, and change the appropirate escp2/media file (probably start by copying the file for one of the K3 printers). Assuming that the K4 ink really does match the K3 ink, you'll get (basically) the same results as a real K3 printer, other than the light black inks. The good news is that you won't need to recompile anything to make this work! After you do this, you'll need to regenerate the PPD file. You should be able to do this with cups-genppdupdate. The HSL curves are not linearization curves; they're color correction curves for people not doing their own color management. You'll be using Uncorrected, Density, or Raw color correction, so they won't come into play. The parameters you're interested in are: + The Value parameters (such as Light Cyan Value) specify the relative darkness of the light vs. dark inks. + The Cutoff parameters now specify the point at which the darker ink is first used, relative to the value of the light ink. + The Scale parameters now specify the amount of light ink used (essentially the density of the light ink). This is the same as the parameters previously called Cutoff. Does this help you get started? -- Robert Krawitz <rl...@al...> Tall Clubs International -- http://www.tall.org/ or 1-888-IM-TALL-2 Member of the League for Programming Freedom -- mail lp...@uu... Project lead for Gutenprint -- http://gimp-print.sourceforge.net "Linux doesn't dictate how I work, I dictate how Linux works." --Eric Crampton |
|
From: Marko M. <mar...@gm...> - 2008-08-08 08:23:42
|
Many thanks for the response. I copied over K3 settings minus gray inks, and the results are very promising - printing "uncorrected" looks almost passable without a profile, while it looked pretty bad with original settings. I can use this as a starting point for icm profiling. I do have some followup questions if I may: Q: In media/<model>.xml files, PrintMethod parameters are different between R280/Claria and R2400/K3, even for same paper types and resolutions. Should my hybrid file have PrintMethod parameters from R280/Claria or R2400/K3? Q: Paper definitions have "SubchannelCutoff" parameter. What is this called in the GUI? Googling it returns nothing. Q: Ink definition file says: ... <shade count="1">1.000000</shade> <shade count="2">1.000000 0.350000</shade> <shade count="2">1.000000 0.200000</shade> ... Does this mean that 35% M is same density as 100% LM, and thus that default setting for "Light Magenta Value" in GUI is 0.35? Marko On Thu, Aug 7, 2008 at 6:13 PM, Robert Krawitz <rl...@al...> wrote: > Marko Milisavljevic wrote: >> >> Hello list, >> >> I have an Epson R280 printer loaded with MIS K4 inks (3rd party >> substitute for Ultrachrome K3 inks), without LK and LLK, of course. I >> am trying to figure out the best way to profile it. I will probably >> use ArgyllCMS for profile generation. >> >> If these inks were standard on this printer, I would treat it is RGB >> printer and print patches using "Uncorrected" mode, but that is not >> the case. I am thus looking for advice on general approach, so I don't >> go barking up too many wrong trees. I imagine I need to do this: >> - Print a gradient for each of the 6 inks using "Raw" option to figure >> out ink limits for individual channels and where is the crossover >> between photo and regular inks. Also print combined inks to figure out >> total ink limit. >> - Tell Gutenprint about these limits, ideally without recompiling >> (simply change settings in driver? modify PPDs or >> /usr/share/gutenprint/5.2/xml/escp2/media/something.xml maybe) >> - Linearize - not exactly sure how. I see Gutenprint has some HSL >> curves in media/something.xml - I assume this is the famed >> "linearization"? I don't see how to linearize individual inks or >> combinations of inks (M+LM) other then some gamma settings. >> Alternatively, print unlinearized with "Density" option and let the >> profiling software sort it out (I'm working in 16-bit). > > So this printer is essentially a CcMmYK printer, correct? > > One option you might start with -- you'll need the latest CVS to do this -- > would be to copy the appropriate data file from escp2/inks and change > escp2/model/model_81.xml to point to the new file, and change the > appropirate escp2/media file (probably start by copying the file for one of > the K3 printers). Assuming that the K4 ink really does match the K3 ink, > you'll get (basically) the same results as a real K3 printer, other than the > light black inks. The good news is that you won't need to recompile > anything to make this work! > > After you do this, you'll need to regenerate the PPD file. You should be > able to do this with cups-genppdupdate. > > The HSL curves are not linearization curves; they're color correction curves > for people not doing their own color management. You'll be using > Uncorrected, Density, or Raw color correction, so they won't come into play. > The parameters you're interested in are: > > + The Value parameters (such as Light Cyan Value) specify the > relative darkness of the light vs. dark inks. > > + The Cutoff parameters now specify the point at which the > darker ink is first used, relative to the value of the light > ink. > > + The Scale parameters now specify the amount of light ink > used (essentially the density of the light ink). This is > the same as the parameters previously called Cutoff. > > Does this help you get started? > > -- > Robert Krawitz <rl...@al...> > > Tall Clubs International -- http://www.tall.org/ or 1-888-IM-TALL-2 > Member of the League for Programming Freedom -- mail lp...@uu... > Project lead for Gutenprint -- http://gimp-print.sourceforge.net > > "Linux doesn't dictate how I work, I dictate how Linux works." > --Eric Crampton > |
|
From: Robert K. <rl...@al...> - 2008-08-08 13:56:25
|
Marko Milisavljevic wrote: > Many thanks for the response. I copied over K3 settings minus gray > inks, and the results are very promising - printing "uncorrected" > looks almost passable without a profile, while it looked pretty bad > with original settings. I can use this as a starting point for icm > profiling. I do have some followup questions if I may: > > Q: In media/<model>.xml files, PrintMethod parameters are different > between R280/Claria and R2400/K3, even for same paper types and > resolutions. > > Should my hybrid file have PrintMethod parameters from R280/Claria or R2400/K3? R280. PrintMethod is a hardware programming parameter (adjusts paper feed speed and Epson knows what else). > Q: Paper definitions have "SubchannelCutoff" parameter. What is this > called in the GUI? Googling it returns nothing. It's the default value for Light Cyan Transition and Light Magenta Transition. Setting Light Cyan Transition and/or Light Magenta Transition is equivalent. > Q: Ink definition file says: > > ... > <shade count="1">1.000000</shade> > <shade count="2">1.000000 0.350000</shade> > <shade count="2">1.000000 0.200000</shade> > ... > > Does this mean that 35% M is same density as 100% LM, and thus that > default setting for "Light Magenta Value" in GUI is 0.35? Yes. -- Robert Krawitz <rl...@al...> Tall Clubs International -- http://www.tall.org/ or 1-888-IM-TALL-2 Member of the League for Programming Freedom -- mail lp...@uu... Project lead for Gutenprint -- http://gimp-print.sourceforge.net "Linux doesn't dictate how I work, I dictate how Linux works." --Eric Crampton |
|
From: Hal V. E. <hv...@as...> - 2008-08-08 01:47:34
|
On Thursday 07 August 2008 05:38:06 pm Marko Milisavljevic wrote: > Hello list, > > I have an Epson R280 printer loaded with MIS K4 inks (3rd party > substitute for Ultrachrome K3 inks), without LK and LLK, of course. I > am trying to figure out the best way to profile it. I will probably > use ArgyllCMS for profile generation. > > If these inks were standard on this printer, I would treat it is RGB > printer and print patches using "Uncorrected" mode, but that is not > the case. I treat my R2400 as a CMYK device why not do the same with this printer? The GutenPrint driver supports it and you will have more control over the printer when you create the profile. That is the profiler will be more "connected" to the actual device this way. It requires a little more work to create a CMYK profile since you have to spend some time getting the K vhannel correctly setup than an RGB profile but the resulting output is better. > I am thus looking for advice on general approach, so I don't > go barking up too many wrong trees. I imagine I need to do this: > - Print a gradient for each of the 6 inks using "Raw" option to figure > out ink limits for individual channels and where is the crossover > between photo and regular inks. My experience with trying RAW mode is that all you end up with is a mess of ink on your paper. Even patches with 30% density had too much ink for the paper. I would be inclined to start out by pretending that the device had the standard inks to see how close or far off Uncorrected mode actually is. You can always increase or decrease the density setting of any channel that is laying down too much or not enough ink and the cross over points between dark and light can also be adjusted in the GIMP plugin (which means this applies to CinePaint if you are using it) as well as PhotoPrint. Although if you use more than one of these whatever tuning you do will have to be duplicated for the others. > Also print combined inks to figure out > total ink limit. > - Tell Gutenprint about these limits, ideally without recompiling > (simply change settings in driver? Again ink limits can be set in the GIMP print plugin and in PhotoPrint. > modify PPDs Users should not modify the PPD. > or > /usr/share/gutenprint/5.2/xml/escp2/media/something.xml maybe) > - Linearize - not exactly sure how. I see Gutenprint has some HSL > curves in media/something.xml - I assume this is the famed > "linearization"? I don't see how to linearize individual inks or > combinations of inks (M+LM) other then some gamma settings. > Alternatively, print unlinearized with "Density" option and let the > profiling software sort it out (I'm working in 16-bit). Linearization is a very hard problem. There are no user land tools to support this with GutenPrint or any of the existing open source printer drivers and doing it by hand is difficult, error prone and time consuming. If the existing curves are even close to OK (IE. farily smooth and monotonic) at this point the best thing to do is let the profiler handle it. But I think you are best off using Uncorrected mode since this at least trys to give you an ink limited linearized output. Again if the density curves of the individual channels are monotonic and reasonably smooth the profiler will do a good job for you. > > Any hints appreciated. > > Marko > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's > challenge Build the coolest Linux based applications with Moblin SDK & win > great prizes Grand prize is a trip for two to an Open Source event anywhere > in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > Gimp-print-devel mailing list > Gim...@li... > https://lists.sourceforge.net/lists/listinfo/gimp-print-devel |
|
From: Marko M. <mar...@gm...> - 2008-08-08 10:36:09
|
I tried printing CMYK but can't figure out how. I think the correct procedure, on a Mac at least is to take a CMYK image and print it while also selecting "CMYK" in Gutenprint driver settings. This appears to be printing RGB, since K gradient looks indistinguishable from gray CMY gradient. How do you make Gutenprint work in CMYK? At least from Photoshop. On Thu, Aug 7, 2008 at 6:47 PM, Hal V. Engel <hv...@as...> wrote: > On Thursday 07 August 2008 05:38:06 pm Marko Milisavljevic wrote: >> I have an Epson R280 printer loaded with MIS K4 inks... > I treat my R2400 as a CMYK device why not do the same with this printer? The > GutenPrint driver supports it and you will have more control over the > printer when you create the profile. That is the profiler will be more > "connected" to the actual device this way. It requires a little more work to > create a CMYK profile since you have to spend some time getting the K > vhannel correctly setup than an RGB profile but the resulting output is > better. |
|
From: Hal V. E. <hv...@as...> - 2008-08-08 17:52:40
|
On Friday 08 August 2008 03:36:18 am Marko Milisavljevic wrote: > I tried printing CMYK but can't figure out how. I think the correct > procedure, on a Mac at least is to take a CMYK image and print it > while also selecting "CMYK" in Gutenprint driver settings. This > appears to be printing RGB, since K gradient looks indistinguishable > from gray CMY gradient. You need to make sure that the CMYK file you are printing actually has a K channel. Most generic RGB -> CMYK conversions will use only process colors (IE. no K channel). But you also need to remember that GutenPrint does use the K channel when it does it's RGB to printer seperations when you are printing an RGB image so even if there is a K channel being printed with your CMYK file this many not be too different from what GutenPrint is sending to the printer. In addition if process grays are a close match to a K then you may not be able to tell the difference between a process gray gradiant and a K gradiant with out the use of a measurement device. Do you have one? > How do you make Gutenprint work in CMYK? You send it a CMYK file and you set the colormode in GutenPrint to CMYK. You need to make sure colorsync is not messing with your stuff. > At > least from Photoshop. I don't know what Photoshop does. Photoshop was designed for Windows and Mac and originally both of these only had RGB print drivers. GutenPrint is closer to being a RIP than a printer driver although you have to use third party front ends to fully utilize this functionality. You might want to have a look at the PhotoPrint front end for GutenPrint. It is specifically for printing images to a GutenPrint device and gives you complete control over how color management is used and how this interacts with GutenPrint assuming that you scan get colorsync to not cause problems. Any image type (even RGB) -> CMYK device profile -> device specfic CMYK. If you are using a CMYK profile to transform the image the file that the print driver gets is CMYK no matter what color space was used for the original. Of course the original image file must be tagged with a profile or you will need to somehow provide this information during the transform. I don't know how ColorSync handles the steps for applying the color transformation but it must do it before it passes the image to GutenPrint if you are going to use it to handle this functionality. On a Linux machine we would use PhotoPrint, CinePaint, Scribus, some other CM aware software or a command line utility to create the device specific CMYK file which is then handed to GutenPrint. With apps like PhotoPrint, CinePaint or Scribus the transformation steps are more or less hidden and there is an automated hand off of the device specific file to GutenPrint. When you generate your profiling target with targen it will be a CMYK target if you are going to create a CMYK profile. You will print it directly to the device through GutenPrint using the same settings as you will use for printing your images in the final printing work flow (IE. all printer driver settings other than paper size and feed options must be the same and so must the paper). You must make sure that ColorSync/CUPS/photoshop do not cause any transformations to occur to the profiling target on it's way to GutenPrint. Since GutenPrint (at least the versions that I have) does not include any cupsICCProfile entries in it's PPDs I would think that you don't have to worry about CUPS causing any issues with this. Since your printer is "customized" if there are cupsICCProfile entries in the PPD you should remove them since these will clearly be incorrect with the new inks. From my experience CinePaint and PhotoPrint will only print 16 bit/channel CMYK files and 8 bit/channel files must be up converted before either of these will accept them for printing. I am not sure if this is a GutenPrint limitation or a limitation in the printing dialogs for these other applications. But I suspect that GutenPrint only accepts 16 bit/channel CMYK files. Robert is this correct? If that is correct then you must make sure that the CMYK files coming out of the device transform are 16 bit/channel. Since you are using 16 bit/channel images this is likely not an issue for your normal work flow. But targen creates 8 bit/channel target images and these will need to be converted to 16 bit/channel before they are sent to GutenPrint. Not a big deal but I though that I would warn you up front. One other ArgyllCMS thing. ArgyllCMS has the ability to produce profiling targets that are optimized for a specific device if there is already an existing profile for that device. The way this works is that you first create a profile using a relatively small number of patchs (perhaps 300 to 500 - IE. one or two pages depending on your spectrophotometer). Using a small number of patches makes it fairly quick to to get this first profile and it should give OK results even with this limited numbr of patches if you should need to use it. Then you use that profile as input into targen which will look at the profile to find areas where it shows signs of having issues such as non- linearities and in those areas it will generate more patches so that the profiling software can get a better handle on what is happening in those places. For this second pass you will want to generate a bigger patch set of perhaps 2000 to 3000 patches. This will take a lot more effort to measure but should result in a very high quality profile. Hal |
|
From: Marko M. <mar...@gm...> - 2008-08-08 19:07:51
|
Thank you for detailed response. On Fri, Aug 8, 2008 at 10:52 AM, Hal V. Engel <hv...@as...> wrote: > On Friday 08 August 2008 03:36:18 am Marko Milisavljevic wrote: > >> I tried printing CMYK but can't figure out how. I think the correct >> procedure, on a Mac at least is to take a CMYK image and print it >> while also selecting "CMYK" in Gutenprint driver settings. This >> appears to be printing RGB, since K gradient looks indistinguishable >> from gray CMY gradient. > > You need to make sure that the CMYK file you are printing actually has a K > channel. Most generic RGB -> CMYK conversions will use only process colors > (IE. no K channel). But you also need to remember that GutenPrint does use > the K channel when it does it's RGB to printer seperations when you are > printing an RGB image so even if there is a K channel being printed with > your CMYK file this many not be too different from what GutenPrint is > sending to the printer. In addition if process grays are a close match to a > K then you may not be able to tell the difference between a process gray > gradiant and a K gradiant with out the use of a measurement device. Do you > have one? I have a CMYK file with side-by-side K and CMY gray gradients. They looks identical on screen, but would be unlikely to look identical when printed without some top-notch profiling, even if just eyeballing. I do have a device to measure with, but I think I just had incorrect settings when printing. >> How do you make Gutenprint work in CMYK? > > You send it a CMYK file and you set the colormode in GutenPrint to CMYK. You > need to make sure colorsync is not messing with your stuff. > >> At least from Photoshop. > > I don't know what Photoshop does. Photoshop was designed for Windows and Mac > and originally both of these only had RGB print drivers. GutenPrint is > closer to being a RIP than a printer driver although you have to use third > party front ends to fully utilize this functionality. You might want to have > a look at the PhotoPrint front end for GutenPrint. It is specifically for > printing images to a GutenPrint device and gives you complete control over > how color management is used and how this interacts with GutenPrint assuming > that you scan get colorsync to not cause problems. What I've been doing in Photoshop is tagging images with sRGB and sending them like that and I think they are not going through another set of conversions. When printing from Photoshop, reagrdless of color management option set in print preview window, Colorsync options in driver settings are grayed out. In other apps there is a choice of CMYK/RGB profiles. I am not sure if that means Photoshop works as if defaults were selected (sRGB/generic CMYK) or what. I'll test it some. > Any image type (even RGB) -> CMYK device profile -> device specfic CMYK. > > If you are using a CMYK profile to transform the image the file that the > print driver gets is CMYK no matter what color space was used for the > original. Of course the original image file must be tagged with a profile or > you will need to somehow provide this information during the transform. > > .... But I suspect that GutenPrint only accepts 16 bit/channel CMYK > files. Robert is this correct? If that is correct then you must make sure > that the CMYK files coming out of the device transform are 16 bit/channel. > Since you are using 16 bit/channel images this is likely not an issue for > your normal work flow. But targen creates 8 bit/channel target images and > these will need to be converted to 16 bit/channel before they are sent to > GutenPrint. Not a big deal but I though that I would warn you up front. When I tried to print in CMYK yesterday, the file was 8-bit. I will retry at 16-bit. About targen... As far as I can tell, it doesn't think in bits - it outputs .ti1 file which contains floating point coordinates. Only with printtarg is the choice about bits made if outputting to TIFF with -t or -T for 8 or 16 bits respectively. Outputting in 8-bit and converting to 16-bit would, at least theoretically, be less precise then creating 16-bit directly from floating point. I suspect the difference is a small fraction of typical error of my spectro though. > One other ArgyllCMS thing. ArgyllCMS has the ability to produce profiling > targets that are optimized for a specific device if there is already an > existing profile for that device. The way this works is that you first > create a profile using a relatively small number of patchs (perhaps 300 to > 500 - IE. one or two pages depending on your spectrophotometer). Using a > small number of patches makes it fairly quick to to get this first profile > and it should give OK results even with this limited numbr of patches if you > should need to use it. Then you use that profile as input into targen which > will look at the profile to find areas where it shows signs of having issues > such as non-linearities and in those areas it will generate more patches so > that the profiling software can get a better handle on what is happening in > those places. For this second pass you will want to generate a bigger patch > set of perhaps 2000 to 3000 patches. This will take a lot more effort to > measure but should result in a very high quality profile. > > Hal I will use ArgyllCMS first for RGB profiling to get a hang of that software, but I would like to eventually do CMYK profiling. How did you actually go about figuring out appropriate GCR settings in ArgyllCMS? Any advice beyond what is written here: http://www.argyllcms.com/doc/Scenarios.html#PP6 Marko |
|
From: Robert K. <rl...@al...> - 2008-08-08 21:27:10
|
Hal V. Engel wrote: > On Friday 08 August 2008 03:36:18 am Marko Milisavljevic wrote: > > When you generate your profiling target with targen it will be a CMYK > target if you are going to create a CMYK profile. You will print it > directly to the device through GutenPrint using the same settings as you > will use for printing your images in the final printing work flow (IE. > all printer driver settings other than paper size and feed options must > be the same and so must the paper). You must make sure that > ColorSync/CUPS/photoshop do not cause any transformations to occur to > the profiling target on it's way to GutenPrint. Since GutenPrint (at > least the versions that I have) does not include any cupsICCProfile > entries in it's PPDs I would think that you don't have to worry about > CUPS causing any issues with this. Since your printer is "customized" if > there are cupsICCProfile entries in the PPD you should remove them since > these will clearly be incorrect with the new inks. The CVS repository (and maybe -beta3, I don't remember) does have cupsICCProfiles for generic sRGB. > From my experience CinePaint and PhotoPrint will only print 16 > bit/channel CMYK files and 8 bit/channel files must be up converted > before either of these will accept them for printing. I am not sure if > this is a GutenPrint limitation or a limitation in the printing dialogs > for these other applications. But I suspect that GutenPrint only accepts > 16 bit/channel CMYK files. Robert is this correct? If that is correct > then you must make sure that the CMYK files coming out of the device > transform are 16 bit/channel. Since you are using 16 bit/channel images > this is likely not an issue for your normal work flow. But targen > creates 8 bit/channel target images and these will need to be converted > to 16 bit/channel before they are sent to GutenPrint. Not a big deal but > I though that I would warn you up front. Gutenprint is perfectly happy with both RGB and CMYK in either 8 or 16 bits, and you can use the same color correction methods with both bit depths (i. e. you can use gamma-corrected 16 bit or uncorrected 8 bit, or vice versa). -- Robert Krawitz <rl...@al...> Tall Clubs International -- http://www.tall.org/ or 1-888-IM-TALL-2 Member of the League for Programming Freedom -- mail lp...@uu... Project lead for Gutenprint -- http://gimp-print.sourceforge.net "Linux doesn't dictate how I work, I dictate how Linux works." --Eric Crampton |
|
From: Hal V. E. <hv...@as...> - 2008-08-08 22:42:19
|
On Friday 08 August 2008 02:27:26 pm Robert Krawitz wrote: > Hal V. Engel wrote: > > On Friday 08 August 2008 03:36:18 am Marko Milisavljevic wrote: > > > > When you generate your profiling target with targen it will be a CMYK > > target if you are going to create a CMYK profile. You will print it > > directly to the device through GutenPrint using the same settings as you > > will use for printing your images in the final printing work flow (IE. > > all printer driver settings other than paper size and feed options must > > be the same and so must the paper). You must make sure that > > ColorSync/CUPS/photoshop do not cause any transformations to occur to > > the profiling target on it's way to GutenPrint. Since GutenPrint (at > > least the versions that I have) does not include any cupsICCProfile > > entries in it's PPDs I would think that you don't have to worry about > > CUPS causing any issues with this. Since your printer is "customized" if > > there are cupsICCProfile entries in the PPD you should remove them since > > these will clearly be incorrect with the new inks. > > The CVS repository (and maybe -beta3, I don't remember) does have > cupsICCProfiles for generic sRGB. Yes beta3 has these and both have a generic CMYK profile. Although these entries point to files that do not exist on my machine. In fact to directories that will not exist on any Linux machine. So this needs to be fixed. If these profiles existed on a Linux machine would they actually get used? If so when would this happen and what rendering intents would be used? Also what is the *StpPPDLocation: "/usr/share/cups/model/gutenprint/5.2/C/ppd/stp-escp2- r2400.5.2.ppd" entry in the PPD for. This also points to a non-existant file. > > > From my experience CinePaint and PhotoPrint will only print 16 > > bit/channel CMYK files and 8 bit/channel files must be up converted > > before either of these will accept them for printing. I am not sure if > > this is a GutenPrint limitation or a limitation in the printing dialogs > > for these other applications. But I suspect that GutenPrint only accepts > > 16 bit/channel CMYK files. Robert is this correct? If that is correct > > then you must make sure that the CMYK files coming out of the device > > transform are 16 bit/channel. Since you are using 16 bit/channel images > > this is likely not an issue for your normal work flow. But targen > > creates 8 bit/channel target images and these will need to be converted > > to 16 bit/channel before they are sent to GutenPrint. Not a big deal but > > I though that I would warn you up front. > > Gutenprint is perfectly happy with both RGB and CMYK in either 8 or 16 > bits, and you can use the same color correction methods with both bit > depths (i. e. you can use gamma-corrected 16 bit or uncorrected 8 bit, > or vice versa). So this is a PhotoPrint/CinePaint issue then. Ok good to know. |
|
From: Hal V. E. <hv...@as...> - 2008-08-08 22:50:45
|
On Friday 08 August 2008 12:07:58 pm Marko Milisavljevic wrote: > Thank you for detailed response. > > On Fri, Aug 8, 2008 at 10:52 AM, Hal V. Engel <hv...@as...> wrote: > > On Friday 08 August 2008 03:36:18 am Marko Milisavljevic wrote: snip > About targen... As far as I can tell, it doesn't think in bits - it > outputs .ti1 file which contains floating point coordinates. Only with > printtarg is the choice about bits made if outputting to TIFF with -t > or -T for 8 or 16 bits respectively. Yes I was thinking printtarg and not targen. These are new options for printtarg. The previous version only ouput ps files and these needed to be converted to tiff or some other raster format and the tools to do that only produced 8 bit files. I have not tried version ArgyllCMS 1.0 yet. snip > > I will use ArgyllCMS first for RGB profiling to get a hang of that > software, but I would like to eventually do CMYK profiling. How did > you actually go about figuring out appropriate GCR settings in > ArgyllCMS? Any advice beyond what is written here: > http://www.argyllcms.com/doc/Scenarios.html#PP6 That is about all that is available on this subject. Basically you want as much K as possible in the grays consistant with having a smooth K tone curve and no artifacts because of the K channel. This is highly dependent on the printer. For printers like the R2400 that have LK and LLK you will likely want to use more of the composit K channel for mid and light grays. But for printers with only a K cart you need to transition from mostly K to mostly process gray farily early to avoid K channel artifacts. Notice how the K channel in the last example on that page is well below the CMY channels until about 45% density. This is about what you need to do with only a K cart to avoid K artifacts like speckels in the mid and light grays. Where as with a printer with LK and LLK you probably want to do something in between the two examples above the last one. This is sort of trial an error thing were you use the process outlined on that web page and some judgement about what might work for your printer to get it in the right ball park with smooth transitions and tone curves. Then you need to do some test prints to make sure you don't have artifacts related to the K channel being too strong. If you have speckels then pull it back some if not then maybe you can push some more K into the grays. Hal |
|
From: Marko M. <mar...@gm...> - 2008-08-08 23:23:50
|
On Fri, Aug 8, 2008 at 3:50 PM, Hal V. Engel <hv...@as...> wrote: > On Friday 08 August 2008 12:07:58 pm Marko Milisavljevic wrote: >> I will use ArgyllCMS first for RGB profiling to get a hang of that >> software, but I would like to eventually do CMYK profiling. How did >> you actually go about figuring out appropriate GCR settings in >> ArgyllCMS? Any advice beyond what is written here: >> http://www.argyllcms.com/doc/Scenarios.html#PP6 > > That is about all that is available on this subject. Basically you want as > much K as possible in the grays consistant with having a smooth K tone curve > and no artifacts because of the K channel. This is highly dependent on the > printer. For printers like the R2400 that have LK and LLK you will likely > want to use more of the composit K channel for mid and light grays. But for > printers with only a K cart you need to transition from mostly K to mostly > process gray farily early to avoid K channel artifacts. Thanks for that clarifying influence of LK & LLK - since I adapted R2400 files to R280+pigment, that means that I should really modify resulting media/....xml file; it is pretty aggressive with GCR for as long as I profile in RGB. Lightroom only allows choice of RGB profiles when doing "managed by application" color management which is why it is nice to have a servicable RGB profile, although I suppose with definition of my own paper types and proper assignment of profiles through colorsync utility, it should successfully print to CMYK-profiled printer where this conversion is colorsync managed. Marko |
×
Want the latest updates on software, tech news, and AI?
Get latest updates about software, tech news, and AI from SourceForge directly in your inbox once a month.
Thanks for helping keep SourceForge clean.
X