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libjpeg-devel-6x — Discussion around maintenance of libjpeg6.x
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From: Bob F. <bfr...@si...> - 2012-04-17 14:21:20
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On Mon, 16 Apr 2012, pV wrote: > Hi,Does Libjpeg support any kind of resizing? I know about smartscale extension but that doesn't > resize the image to the size asked for, it only does it in a ratio of N/8. > Is there any other solution, to resize a given image to the desired height and width? I think that you will need an image processing package for that. Bob -- Bob Friesenhahn bfr...@si..., http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ |
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From: pV <pve...@gm...> - 2012-04-17 06:06:18
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Hi, Does Libjpeg support any kind of resizing? I know about smartscale extension but that doesn't resize the image to the size asked for, it only does it in a ratio of N/8. Is there any other solution, to resize a given image to the desired height and width? Thanks. |
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From: 杨辉强 <hui...@yu...> - 2011-11-10 08:57:12
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Hi, all:
I am newbie to libjpeg. In the example code the compressed data can
be save to a file.
Now I want save the compressed data to memory such as a unsigned
array. I have read the
FAQ but can't find any hints. Could you give me some instructions.
Thank you!
Best wishes!
|
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From: 杨辉强 <hui...@yu...> - 2011-11-10 08:36:38
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Thank you. |
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From: wan_sapper <wan...@ya...> - 2011-10-31 04:14:04
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Good Day, I have created my own DCT calculation arrays. Therefore for 256 * 256 pixels size of image, I have prepared 1024 blocks of DCT arrays (8 * 8). How do I use jpeg_write_coefficients to write my arrays values into jpeg file using jpeg_write_coefficients. jpeg_write_coefficients needs jvirt_barray_ptr * coef_arrays. How do I create this? Thanks. |
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From: PrathviRaj S.G. <pra...@gm...> - 2011-10-25 11:09:13
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Hi, I am computer science post graduate student . I want to take up a small project in C, so I decided to go with building an application which reduces image size without compromising with the quality of an image. I need help and suggestion about how to go ahead with this project using *libjpeg * library. Thank You -- Regards, PrathviRaj S.G. |
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From: Bob F. <bfr...@si...> - 2011-07-28 00:41:47
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On Mon, 25 Jul 2011, Alex Leach wrote: > > I’ve noticed when running configure on my Mac Pro, ltconfig does not pick up my host system type > (x86_64-apple-darwin10.8.0). Is this deliberate? This can be fixed by updating the config.guess file shipped with jpeg-6b. I > attach the version that comes with libpng-1.5.4, which successfully finds the host type. The jpeg 6b release was made in 1998 and I don't know if Darwin even existed yet. What jpeg 6b package did you use? Note that the official IJG JPEG (not maintained by folks on this list) is now up to 8c. Bob -- Bob Friesenhahn bfr...@si..., http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ |
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From: Drip S. <dri...@gm...> - 2011-04-15 19:17:46
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Hello,
I am working on a small project which needs to rewrite a tag after
jpeg_finish_compress( &cinfo ); is called.
The procedure is:
1. jpeg_write_marker
...
2. while(...)
jpeg_write_scanlines
...
3. jpeg_finish_compress
4. update the marker we have written
The tag I have written first is not correct because it needs the size
of jpeg file. I plan to update the tag after jpeg_finish_compress. Is
it possible to tell the position of each tag before writing it to the file
so that I can rewrite it without parsing jpeg file again. I tried ftell(),
and it doesn't work well.
Thanks a lot!
Dripstone
|
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From: Lluís B. i R. <vir...@gm...> - 2010-10-30 22:45:50
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Hello, I just discovered this mailing list, and I just thought that it may be of interest to the users here some software I wrote years ago: http://vicerveza.homeunix.net/~viric/soft/qjpegrest/ It allows manually tweaking the decompression of JPEG using even the DCT coefficients saved in the JPEG stream, by choosing few parameters of some specially chosen published algorithms. I'm not continuing any development on that, specially because I found noone having any interest in doing an effort to get better decoded JPEG pictures. Best regards, Lluís. |
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From: Lluís B. i R. <vir...@gm...> - 2010-10-30 22:40:37
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Hello, I'm trying to make a program that will not decode full pictures into a single big JSAMPARRAY. So if the user wants to see only 10% of the lines, then I want to be able to decode 10% of the lines. I've tried to set output_scanline to something bigger than zero, but that looks like making zero effect - the lines I get with jpeg_read_scanline start from 0 regardless of the initial output_scanline value. What can I do to get only some specific scanlines decoded? I'm using libjpeg-8. Thank you, Lluís. |
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From: linux n. <lin...@gm...> - 2010-06-29 01:15:58
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Hi, I am using latest libjpeg and I need to know how to do scaling. My embedded target screen resolution is 640x240 and my jpeg picture is of 800x600. On doing decompression, I belive I need to set the values in jpeg_decompress_struct for scaling, but not sure. can anyone let me know with an example? Thanks |
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From: Markus M. <mam...@ht...> - 2010-06-17 08:02:35
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Tom Lane <tg...@ss...>: > > is there a way to get the unquantized coefficients from libjpeg during a > > compression process? What I want to do is to see how the coefficients got > > rounded after they got divided with the quantization table. How could I > > achieve this? > > Insert some printf's, maybe? There's certainly no provision for > exposing that to the application. I meant an interface to libjpeg, so a calling application has direct access to the intermediate steps, eg coefficients before rounding. But yes, as you said, this is not a common use case, maybe I'm better of writing a simple jpeg compressor with this feature for my application. best Markus |
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From: Tom L. <tg...@ss...> - 2010-06-17 03:32:09
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Markus Messmer <mam...@ht...> writes: > is there a way to get the unquantized coefficients from libjpeg during a > compression process? What I want to do is to see how the coefficients got > rounded after they got divided with the quantization table. How could I > achieve this? Insert some printf's, maybe? There's certainly no provision for exposing that to the application. regards, tom lane |
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From: Markus M. <mam...@ht...> - 2010-06-16 12:07:02
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Hi all, is there a way to get the unquantized coefficients from libjpeg during a compression process? What I want to do is to see how the coefficients got rounded after they got divided with the quantization table. How could I achieve this? Best regards Markus |
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From: Galileo`s <liu...@qq...> - 2010-05-16 03:25:42
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hi,all.im from China,im doing a project which applies this LibJpeg to convert RGB to JPEG.mealwhile,im using uCGUI(know ucOSII??),but uCGUI only uses the part of decompression.i wanna send the data compressed by LibJpeg to my phone via MMS.i have a OV9650 camera .it can transferes (SCCB interface)RGB data to my s3c2440 ARM core. i have a little about LibJpeg and JPEG ,i read the introduce to LibJpeg. i wonder whether the data compressed by LibJpeg is the .jpg format.can it be read by phone directly??if not ,is it means that i must add some other info to the data compressed by LibJpeg. can you give me some suggestion? im sorry for my poor english. |
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From: Galileo`s <liu...@qq...> - 2010-05-14 12:32:32
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hi,all.im from China,im doing a project which applies this LibJpeg to convert RGB to JPEG.mealwhile,im using uCGUI(know ucOSII??),but uCGUI only uses the part of decompression.i wanna send the data compressed by LibJpeg to my phone via MMS.i have a OV9650 camera .it can transferes (SCCB interface)RGB data to my s3c2440 ARM core. i have a little about LibJpeg and JPEG ,i read the introduce to LibJpeg. i wonder whether the data compressed by LibJpeg is the .jpg format.can it be read by phone directly??if not ,is it means that i must add some other info to the data compressed by LibJpeg. can you give me some suggestion? im sorry for my poor english. |
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From: Tom L. <tg...@ss...> - 2010-04-29 22:42:24
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Justin Wetherell <phi...@gm...> writes: > I believe there is a memory leak in the jpeg_write_scanlines() function. The > code below takes a frame image from a dc1394 camera and turns it into a jpeg > inside a while loop. The memory usage increases 0.1% about every 5 seconds > on an embedded ARM processor with very little memory and processor power. I'm not sure what jpeg_mem_dest is --- it's not part of libjpeg 6b. I'd bet the leak is within the code installed by that. It is very highly unlikely that a leak in jpeg_write_scanlines proper would have escaped notice for all these years. (But are you sure it's a leak at all? I assume from the name that this is code meant to store the resulting JPEG data in memory. Perhaps you're just watching the accumulation of output data?) regards, tom lane |
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From: Tom L. <tg...@ss...> - 2010-04-29 22:41:29
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Justin Wetherell <phi...@gm...> writes: > Actually, sorry I am using the libjpeg v8a version which is where the > jpeg_mem_dest. I didn't realize this is the specific v6 distro list. Is > there a v8 mailing list that you know of? I don't know of one. I'd suggest reporting the problem to Guido directly --- I assume there's a contact address in the v8 docs ... regards, tom lane |
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From: Justin W. <phi...@gm...> - 2010-04-29 22:37:16
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Actually, sorry I am using the libjpeg v8a version which is where the jpeg_mem_dest. I didn't realize this is the specific v6 distro list. Is there a v8 mailing list that you know of? On Thu, Apr 29, 2010 at 6:23 PM, Tom Lane <tg...@ss...> wrote: > Justin Wetherell <phi...@gm...> writes: > > I believe there is a memory leak in the jpeg_write_scanlines() function. > The > > code below takes a frame image from a dc1394 camera and turns it into a > jpeg > > inside a while loop. The memory usage increases 0.1% about every 5 > seconds > > on an embedded ARM processor with very little memory and processor power. > > I'm not sure what jpeg_mem_dest is --- it's not part of libjpeg 6b. > I'd bet the leak is within the code installed by that. It is very > highly unlikely that a leak in jpeg_write_scanlines proper would > have escaped notice for all these years. > > (But are you sure it's a leak at all? I assume from the name that > this is code meant to store the resulting JPEG data in memory. > Perhaps you're just watching the accumulation of output data?) > > regards, tom lane > |
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From: Justin W. <phi...@gm...> - 2010-04-29 21:19:47
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I believe there is a memory leak in the jpeg_write_scanlines() function. The
code below takes a frame image from a dc1394 camera and turns it into a jpeg
inside a while loop. The memory usage increases 0.1% about every 5 seconds
on an embedded ARM processor with very little memory and processor power.
static struct jpeg_compress_struct cinfo;
static struct jpeg_error_mgr jerr;
static JSAMPROW row_pointer[1];
cinfo.err = jpeg_std_error( &jerr );
jpeg_create_compress(&cinfo);
while( !pglobal->stop ) {
pthread_mutex_lock( &pglobal->db );
err = dc1394_capture_dequeue(camera, DC1394_CAPTURE_POLICY_WAIT,
&frames[0]);
memcpy(latestFrame, frames[0]->image, frameWidth * frameHeight);
static unsigned char *jpeg = NULL;
static long unsigned jpegSize = 0;
jpeg_mem_dest(&cinfo, &jpeg, &jpegSize);
cinfo.image_width = frameWidth;
cinfo.image_height = frameHeight;
cinfo.input_components = 1;
cinfo.in_color_space = JCS_GRAYSCALE;
jpeg_set_defaults( &cinfo );
jpeg_start_compress( &cinfo, TRUE );
while( cinfo.next_scanline < cinfo.image_height ) {
row_pointer[0] = &latestFrame[ cinfo.next_scanline *
cinfo.image_width * cinfo.input_components];
jpeg_write_scanlines( &cinfo, row_pointer, 1 );
}
jpeg_finish_compress( &cinfo );
err = dc1394_capture_enqueue(camera, frames[0]);
pglobal->size = jpegSize;
memcpy(pglobal->buf, jpeg, pglobal->size);
pthread_cond_broadcast(&pglobal->db_update);
pthread_mutex_unlock( &pglobal->db );
if(trigger==0)usleep(1000*delay);
}
jpeg_destroy_compress( &cinfo );
If I comment out the code from "jpeg_start_compress( &cinfo, TRUE );" to
"jpeg_finish_compress( &cinfo );" (like below) the memory usage stays
consistent.
//jpeg_set_defaults( &cinfo );
//jpeg_start_compress( &cinfo, TRUE );
//while( cinfo.next_scanline < cinfo.image_height ) {
// row_pointer[0] = &latestFrame[ cinfo.next_scanline *
cinfo.image_width * cinfo.input_components];
// jpeg_write_scanlines( &cinfo, row_pointer, 1 );
//}
//jpeg_finish_compress( &cinfo );
Any help would be appreciated,
-Justin
|
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From: Tom L. <tg...@ss...> - 2010-02-27 02:53:47
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Jonathan Wallace <jwa...@li...> writes: > There is a glaring omission from it which anyone who uses *nix will notice right away. > ./configure > make > sudo make install What's wrong with that? > You can never install anything on the Mac without going through the > superuser. Sure, that's what the "sudo" is for. regards, tom lane |
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From: Bob F. <bfr...@si...> - 2010-02-26 21:59:11
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On Fri, 26 Feb 2010, Jonathan Wallace wrote: > There is a glaring omission from it which anyone who uses *nix will notice right away. > ./configure > make > sudo make install > > You can never install anything on the Mac without going through the > superuser. I'm fairly certain it's the same way on all *nix > distribution. How this hasn't been fixed yet is beyond me. This is not true. The person building the software could use an installation prefix where their user ID has write access. I am glad that you were able to figure this out even though the documentation is lacking. Bob -- Bob Friesenhahn bfr...@si..., http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ |
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From: Jonathan W. <jwa...@li...> - 2010-02-26 19:52:53
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There is a glaring omission from it which anyone who uses *nix will notice right away. ./configure make sudo make install You can never install anything on the Mac without going through the superuser. I'm fairly certain it's the same way on all *nix distribution. How this hasn't been fixed yet is beyond me. |
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From: Guido V. <gu...@jp...> - 2009-10-07 13:08:07
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Hello Allan > > And even v7 is fading fast into history. > > v8 is ready here and will be released on 1-Jan-2010. > > > > Is there going to be api changes this time? No. That's why it was good to release v7 so that the changes can be resolved now. No further adaptions should be necessary for v8. But there are of course reasons for the jump from v7 to v8: Applications need again to be recompiled, due to extension of the parameter master records, and there will be a format extension which will introduce new flavors of JPEG files, similar to adding progressive support in v6 and arithmetic support in v7. > The libjpeg6 to 7 upgrade was complicated by the change in scaling. > > jpeg-6b: Currently, the only supported scaling ratios are 1/1, 1/2, 1/4, > and 1/8. > jpeg-7: Currently, the supported scaling ratios are 8/N with all N from > 1 to 16. It was not complicated, but people just got confused that scaling has now been introduced also for the compression side. The 8/N figure is for *compression*! For decompression it is N/8 and the old cases are a subset thereof (N=8,4,2,1). > Also, is there a mailing list for the development of libjpeg apart from > this one? There is no mailing list. I will make available pre-release versions of v8 on jpegclub.org in some weeks (when adaptions of the Jpegcrop sample program are finished), similar as done with v7. Regards Guido |
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From: Allan M. <mcr...@ho...> - 2009-10-07 12:56:33
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Guido Vollbeding wrote: > I have noticed that jpeg-7 is available on Google Code under GhostScript > (will find this when searching for "ijg jpeg-7" on google). > And even v7 is fading fast into history. > v8 is ready here and will be released on 1-Jan-2010. > Is there going to be api changes this time? The libjpeg6 to 7 upgrade was complicated by the change in scaling. jpeg-6b: Currently, the only supported scaling ratios are 1/1, 1/2, 1/4, and 1/8. jpeg-7: Currently, the supported scaling ratios are 8/N with all N from 1 to 16. Also, is there a mailing list for the development of libjpeg apart from this one? Allan |
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