I have just started to use this (apparently) useful program. I am trying to assess the resolution achieved by a high resolution (1800 dpi) scanner across its platen. Attached is a scan of a target which I have opened in the various ways suggested in the manual, including manual edge selection. But no results or error messages have appeared and the green bar at the bottom stays at 100% whether anything is opened or not.
Is the target or image unsuitable? Or have I pressed the wrong button?
I have managed to open and process your image fairly easily. I would recommend to try setting the "Threshold" parameter to 0.4 as shown in my attached screenshot; this seem to be enough to allow the whole image to be processed using the usual "File->Open" method. After that I expanded the tree-view triangle in the "Data set" list on the right, and clicked on the "annotated" list entry. Then I clicked on the cyan-coloured text that says "0.10" on the leftmost edge of the square, which caused the blue dot to appear, and open up the "SFR / MTF curve" window.
I have also attached a screenshot showing the output. I am somewhat troubled by all the ghost images (I circled some of them in red). These could potentially cause trouble, e.g., you can see that the annotation for the top edge is shifted to the right-hand side of the edge rather than appearing in the centre of the edge. If you were to compute the MTF across one of these "shadows" the results will likely be corrupted. The safest strategy would be to use the manual edge selection workflow to carefully pick only homogenous edge sections.
It looks like you were scanning a transmissive target (e.g., acetate foil). My guess is that the shadows are caused by the light reflecting off the top lid of the scanner. You could try covering the foil with a blank sheet of paper to minimize the shadows, but the non-zero thickness of the foil could still cause some shadowing (perhaps making it less obvious, which would be worse).
I also see that the white parts of the image are very nearly over-exposed. If you have a control that reduces the scanner exposure, I would recommend that you dial it down so that the white parts of the image are not fully saturated. You will see a little triangle pop up on the histogram in manual edge selection mode with your sample image; the goal would be to reduce scanner exposure until MTF Mapper no long adds the warning triangle to the histogram. Looking at the actual SFR, I think you may actually be safe with the current scanner settings, I'm just being cautious here because an overexposed image could lead to clipping, which will introduce non-linearity to the image data, leading to over-estimation of the MTF values. A slight underexposure is preferable to a slight overexposure with these measurements.
Anyhow, that's a lot for a first reply, please let me know if you have more questions!
Thank you for the prompt and useful guidance.
I got confused in the early instructions , because of the wealth of choices. Your first paragraph below guided me quickly up the learning curve. Perhaps include it as part of the beginner's guide.
I agree about the distracting shadows, which as you suggest are probably due to the cover being placed onto the targets. I shall raise it a couple of cm and perhaps place a grey sheet over the whole. I am using chrome targets on 1.5 mm glass, with edges created at 256k dpi resolution.
Line identification: The automatic line identification is a bit iffy.
Lines on this checkerboard is are only partially identified. [cid:image001.png@01DC7A94.6F623D90]
And this one (copied from the centre of the image) has no recognised lines. They are both supplied at the same resolution, just different qross areas. [cid:image002.png@01DC7A95.173976F0]
And is confused by multiple lines (the 16 bit file -actually 8bit)
A number of processing issues:
It would be useful if the log.txt file recorded the file name whose processing it is recording.
MTF hangs at 30-50% with images it is unhappy with, so I close it down by clicking X at the top right corner. Then I get a message that a number of Temp directories need to be and will be deleted. But they aren't. And I can't.
Task Manager tells me that there are 4 each of mtf_mapper and mtf_mapper_gui still active and running.
I shall now restart the computer to see if the temp files get deleted, or deletable.
They were not deleted on startup but this allowed me to delete them.
However, another checkerboard image hangs at 50%. When I close MFTMapper, the temp folder and Task Manager both hold onto the the files and processes, which are still there when I re-open MFT. So it looks as though closing MFT on a hard stop does not completely clear out and stop the ongoing processes.
It is really useful having all the temp files etc named with mft... Thank you
I have managed to open and process your image fairly easily. I would recommend to try setting the "Threshold" parameter to 0.4 as shown in my attached screenshot; this seem to be enough to allow the whole image to be processed using the usual "File->Open" method. After that I expanded the tree-view triangle in the "Data set" list on the right, and clicked on the "annotated" list entry. Then I clicked on the cyan-coloured text that says "0.10" on the leftmost edge of the square, which caused the blue dot to appear, and open up the "SFR / MTF curve" window.
I have also attached a screenshot showing the output. I am somewhat troubled by all the ghost images (I circled some of them in red). These could potentially cause trouble, e.g., you can see that the annotation for the top edge is shifted to the right-hand side of the edge rather than appearing in the centre of the edge. If you were to compute the MTF across one of these "shadows" the results will likely be corrupted. The safest strategy would be to use the manual edge selection workflow to carefully pick only homogenous edge sections.
It looks like you were scanning a transmissive target (e.g., acetate foil). My guess is that the shadows are caused by the light reflecting off the top lid of the scanner. You could try covering the foil with a blank sheet of paper to minimize the shadows, but the non-zero thickness of the foil could still cause some shadowing (perhaps making it less obvious, which would be worse).
I also see that the white parts of the image are very nearly over-exposed. If you have a control that reduces the scanner exposure, I would recommend that you dial it down so that the white parts of the image are not fully saturated. You will see a little triangle pop up on the histogram in manual edge selection mode with your sample image; the goal would be to reduce scanner exposure until MTF Mapper no long adds the warning triangle to the histogram. Looking at the actual SFR, I think you may actually be safe with the current scanner settings, I'm just being cautious here because an overexposed image could lead to clipping, which will introduce non-linearity to the image data, leading to over-estimation of the MTF values. A slight underexposure is preferable to a slight overexposure with these measurements.
Anyhow, that's a lot for a first reply, please let me know if you have more questions!
I have just started to use this (apparently) useful program. I am trying to assess the resolution achieved by a high resolution (1800 dpi) scanner across its platen. Attached is a scan of a target which I have opened in the various ways suggested in the manual, including manual edge selection. But no results or error messages have appeared and the green bar at the bottom stays at 100% whether anything is opened or not.
Is the target or image unsuitable? Or have I pressed the wrong button?
Hi!
I have managed to open and process your image fairly easily. I would recommend to try setting the "Threshold" parameter to 0.4 as shown in my attached screenshot; this seem to be enough to allow the whole image to be processed using the usual "File->Open" method. After that I expanded the tree-view triangle in the "Data set" list on the right, and clicked on the "annotated" list entry. Then I clicked on the cyan-coloured text that says "0.10" on the leftmost edge of the square, which caused the blue dot to appear, and open up the "SFR / MTF curve" window.
I have also attached a screenshot showing the output. I am somewhat troubled by all the ghost images (I circled some of them in red). These could potentially cause trouble, e.g., you can see that the annotation for the top edge is shifted to the right-hand side of the edge rather than appearing in the centre of the edge. If you were to compute the MTF across one of these "shadows" the results will likely be corrupted. The safest strategy would be to use the manual edge selection workflow to carefully pick only homogenous edge sections.
It looks like you were scanning a transmissive target (e.g., acetate foil). My guess is that the shadows are caused by the light reflecting off the top lid of the scanner. You could try covering the foil with a blank sheet of paper to minimize the shadows, but the non-zero thickness of the foil could still cause some shadowing (perhaps making it less obvious, which would be worse).
I also see that the white parts of the image are very nearly over-exposed. If you have a control that reduces the scanner exposure, I would recommend that you dial it down so that the white parts of the image are not fully saturated. You will see a little triangle pop up on the histogram in manual edge selection mode with your sample image; the goal would be to reduce scanner exposure until MTF Mapper no long adds the warning triangle to the histogram. Looking at the actual SFR, I think you may actually be safe with the current scanner settings, I'm just being cautious here because an overexposed image could lead to clipping, which will introduce non-linearity to the image data, leading to over-estimation of the MTF values. A slight underexposure is preferable to a slight overexposure with these measurements.
Anyhow, that's a lot for a first reply, please let me know if you have more questions!
Regards,
Frans
Frans
Thank you for the prompt and useful guidance.
I got confused in the early instructions , because of the wealth of choices. Your first paragraph below guided me quickly up the learning curve. Perhaps include it as part of the beginner's guide.
I agree about the distracting shadows, which as you suggest are probably due to the cover being placed onto the targets. I shall raise it a couple of cm and perhaps place a grey sheet over the whole. I am using chrome targets on 1.5 mm glass, with edges created at 256k dpi resolution.
Line identification: The automatic line identification is a bit iffy.
Lines on this checkerboard is are only partially identified.
[cid:image001.png@01DC7A94.6F623D90]
And this one (copied from the centre of the image) has no recognised lines. They are both supplied at the same resolution, just different qross areas.
[cid:image002.png@01DC7A95.173976F0]
And is confused by multiple lines (the 16 bit file -actually 8bit)
A number of processing issues:
It would be useful if the log.txt file recorded the file name whose processing it is recording.
MTF hangs at 30-50% with images it is unhappy with, so I close it down by clicking X at the top right corner. Then I get a message that a number of Temp directories need to be and will be deleted. But they aren't. And I can't.
Task Manager tells me that there are 4 each of mtf_mapper and mtf_mapper_gui still active and running.
I shall now restart the computer to see if the temp files get deleted, or deletable.
They were not deleted on startup but this allowed me to delete them.
However, another checkerboard image hangs at 50%. When I close MFTMapper, the temp folder and Task Manager both hold onto the the files and processes, which are still there when I re-open MFT. So it looks as though closing MFT on a hard stop does not completely clear out and stop the ongoing processes.
It is really useful having all the temp files etc named with mft... Thank you
Next stage - rescan the targets.
Velson Horie
www.horie.co.uk
From: discussion@mtfmapper.p.re.sourceforge.net discussion@mtfmapper.p.re.sourceforge.net On Behalf Of Frans van den Bergh
Sent: 30 December 2025 13:51
To: [mtfmapper:discussion] general@discussion.mtfmapper.p.re.sourceforge.net
Subject: [mtfmapper:discussion] Re: No results
Hi!
I have managed to open and process your image fairly easily. I would recommend to try setting the "Threshold" parameter to 0.4 as shown in my attached screenshot; this seem to be enough to allow the whole image to be processed using the usual "File->Open" method. After that I expanded the tree-view triangle in the "Data set" list on the right, and clicked on the "annotated" list entry. Then I clicked on the cyan-coloured text that says "0.10" on the leftmost edge of the square, which caused the blue dot to appear, and open up the "SFR / MTF curve" window.
I have also attached a screenshot showing the output. I am somewhat troubled by all the ghost images (I circled some of them in red). These could potentially cause trouble, e.g., you can see that the annotation for the top edge is shifted to the right-hand side of the edge rather than appearing in the centre of the edge. If you were to compute the MTF across one of these "shadows" the results will likely be corrupted. The safest strategy would be to use the manual edge selection workflow to carefully pick only homogenous edge sections.
It looks like you were scanning a transmissive target (e.g., acetate foil). My guess is that the shadows are caused by the light reflecting off the top lid of the scanner. You could try covering the foil with a blank sheet of paper to minimize the shadows, but the non-zero thickness of the foil could still cause some shadowing (perhaps making it less obvious, which would be worse).
I also see that the white parts of the image are very nearly over-exposed. If you have a control that reduces the scanner exposure, I would recommend that you dial it down so that the white parts of the image are not fully saturated. You will see a little triangle pop up on the histogram in manual edge selection mode with your sample image; the goal would be to reduce scanner exposure until MTF Mapper no long adds the warning triangle to the histogram. Looking at the actual SFR, I think you may actually be safe with the current scanner settings, I'm just being cautious here because an overexposed image could lead to clipping, which will introduce non-linearity to the image data, leading to over-estimation of the MTF values. A slight underexposure is preferable to a slight overexposure with these measurements.
Anyhow, that's a lot for a first reply, please let me know if you have more questions!
Regards,
Frans
Attachments:
No resultshttps://sourceforge.net/p/mtfmapper/discussion/general/thread/f4ba2117cb/?limit=25#5ecb/d59b
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