08-13-2017, 07:17 PM
First, let me say that my problem may not be with GIMP but since I'm using and trying to learn GIMP this seemed like the best forum for discussion. As a result, of some success using GIMP to edit images obtained by scanning old and often decaying photographs I decided to upgrade my camera to something capable of producing images in raw format. I now have a Canon EOS Rebel T6 set to produce raw images. I'm running GIMP on Win7 and have installed UFraw Version 0.19.2 in order open the raw image files.
The problem is that there is a huge difference in the picture being displayed depending on what software is being used for viewing it. When I say view I mean that I have not attempted to do any editing (i.e., make any changes). I don't know how to demonstrate the problem with raw images that you forum users may not be able to process. Fortunately, the problem which at present is entirely about appearance is preserved when different software is used to prepare .jpg files for reference purposes. I've uploaded those .jpg files to Google Photos in order to demonstrate the problem being described. While Google Photos does perform conversion of it's own, such as scaling, the defects I'm describing are preserved in these images. For example,
Here (https://goo.gl/photos/sAStoedrd6KEi31cA) is an image prepared by DPP4 (i.e., Canon Digital Photo Professional 4). Based on the subject of the photograph this one is consistent with photographer's expectation.
Here (https://goo.gl/photos/o81YQcLsxK4XzYJ46) is the exact same image prepared by GIMP.
When I say same image it means the same raw file converted to .jpg format by the respective software. Insofar as the raw file has to be processed by UFraw in order for GIMP to obtain an image, it is quite reasonable to conclude that UFraw may have done something to it. In fact, the process of opening the file in GIMP results in the invocation of UFraw which does display the image prior to forwarding it to GIMP. The view displayed in UFraw does look like what is is displayed in GIMP and the resulting .jpg created by GIMP. You might conclude it is obvious that UFraw changed it which in this case amounts to pretty dramatic alteration, especially given that I made no attempt to change anything.
However, that is not the end of story. I also use Google Picasa for organizing photographs on my computer. Interestingly, Picasa is able to handle the raw files. In fact, it looks like Picasa knows how to process them even though Windows does not. For example,
Here (https://goo.gl/photos/ex25PVZ52eWLF9Ki7) is the exact same image prepared by Picasa. Picasa is also the program that is launched when I open a raw file in Windows Explorer. While, to me, it looks like the .jpg image prepared by Picasa is similar in appearance to the defective one prepared by GIMP they are distinguishable from each other. However, both of these images appear to have the same defects when compared to what was expected from the actual subject of the photo. The image prepared by DDP4 is consistent with expectation. Interestingly when the Picasa viewer is launched it momentarily displays an image that looks much more like the one prepared by DPP4 but it momentarily reverts to the appearance of the referenced image prepared by Picasa (i.e., like casting a dark shadow over the entire image).
My apologies for the verbosity but the big problem here is the extent of the inconsistency in results. Absent some kind of explanation for what is causing these variations how can one have any confidence in the accuracy of the results obtained from using any of this, or for that matter other, software for editing graphic images. How can this phenomenon be reconciled? I hope there is a simple explanation that amounts to my error (i.e., lack of knowledge). Can anyone explain?
The problem is that there is a huge difference in the picture being displayed depending on what software is being used for viewing it. When I say view I mean that I have not attempted to do any editing (i.e., make any changes). I don't know how to demonstrate the problem with raw images that you forum users may not be able to process. Fortunately, the problem which at present is entirely about appearance is preserved when different software is used to prepare .jpg files for reference purposes. I've uploaded those .jpg files to Google Photos in order to demonstrate the problem being described. While Google Photos does perform conversion of it's own, such as scaling, the defects I'm describing are preserved in these images. For example,
Here (https://goo.gl/photos/sAStoedrd6KEi31cA) is an image prepared by DPP4 (i.e., Canon Digital Photo Professional 4). Based on the subject of the photograph this one is consistent with photographer's expectation.
Here (https://goo.gl/photos/o81YQcLsxK4XzYJ46) is the exact same image prepared by GIMP.
When I say same image it means the same raw file converted to .jpg format by the respective software. Insofar as the raw file has to be processed by UFraw in order for GIMP to obtain an image, it is quite reasonable to conclude that UFraw may have done something to it. In fact, the process of opening the file in GIMP results in the invocation of UFraw which does display the image prior to forwarding it to GIMP. The view displayed in UFraw does look like what is is displayed in GIMP and the resulting .jpg created by GIMP. You might conclude it is obvious that UFraw changed it which in this case amounts to pretty dramatic alteration, especially given that I made no attempt to change anything.
However, that is not the end of story. I also use Google Picasa for organizing photographs on my computer. Interestingly, Picasa is able to handle the raw files. In fact, it looks like Picasa knows how to process them even though Windows does not. For example,
Here (https://goo.gl/photos/ex25PVZ52eWLF9Ki7) is the exact same image prepared by Picasa. Picasa is also the program that is launched when I open a raw file in Windows Explorer. While, to me, it looks like the .jpg image prepared by Picasa is similar in appearance to the defective one prepared by GIMP they are distinguishable from each other. However, both of these images appear to have the same defects when compared to what was expected from the actual subject of the photo. The image prepared by DDP4 is consistent with expectation. Interestingly when the Picasa viewer is launched it momentarily displays an image that looks much more like the one prepared by DPP4 but it momentarily reverts to the appearance of the referenced image prepared by Picasa (i.e., like casting a dark shadow over the entire image).
My apologies for the verbosity but the big problem here is the extent of the inconsistency in results. Absent some kind of explanation for what is causing these variations how can one have any confidence in the accuracy of the results obtained from using any of this, or for that matter other, software for editing graphic images. How can this phenomenon be reconciled? I hope there is a simple explanation that amounts to my error (i.e., lack of knowledge). Can anyone explain?