Tim Woodward
Member
After reading what seems like a years worth of discussion in this group about the above subject I thought (now that I have my own Dimage 7!) I would check out these phenomena myself and publish the results should anyone have got this far!
The general argument seems to go that colour matching the image produced by the D7 on your computer screen and comparing this with how you remember the original scene produces variable results - many of you seem to think using DIVU adds an incorrect colour balance to the image, and yet others, Minolta and some reviewers seem to think DIVU is indispensable in getting the D7 colour space (which is a wider gamut than typical) into what is a more standard and presumably more accurate rendition.
My D7 actually arrived with an extra slip of paper in the packing, obviously added after production and I quote from this “The DiMAGE7 utilises a wider colourspace than most consumer digital cameras. Part of this colourspace is created with information achieved from the CxProcess image processing system. To ensure that your images maintain faithful yet vivid colours it is preferable to use the Minolta Image Viewer Utility to acquire your images from the camera”
So I set about viewing a fairly varied set of images taken over the last few days with my D7 - in various colourspaces and with various options set (on a PC not MAC I’m afraid).
Images were taken at the typical ‘default’ highest JPEG (RAW imports into DIVU are another issue entirely!) quality and size - i.e. ‘Fine’ and ‘2560’.
As far as ‘converted’ images were concerned, these tests were performed loading images into DIVU:
1. With Colour Matching ‘on’
2. With various Output Colour Spaces as alternatives (including ICC profile matching)
3. Viewed both with and without Basic Colour Management enabled within PaintShop Pro 7
4. Saved as TIFF files (JPEG was avoided so as not to increase lossy compression with each save)
As far as ‘unconverted’ images were concerned, I simply dragged the images directly from the card untouched and dropped them into a folder entitled ‘un-converted’ for reference. Opening them directly in PSP for comparison.
Obviously certain criteria affect the outcome of these results and it is important that you have a level playing field for colour management to work. For instance, if you have no colour management options set within your image manipulation program then the results will be very different than if you use a colour management profile. Also how the image looks on the Web (browser rendered ) or on another monitor with different colourspace or profile is totally unpredictable (which is where I think most of the argument comes from). Also your monitor Gamma should be calibrated using what ever tools you have - I used the options within PSP 7.
So what did I find - well, in the event I found that all of the colour matching alternatives within DIVU resulted in darker and more colourful images than those that were unconverted. With colour management on in PSP and choosing the sRGB profile (installed by default in the windows/system/color folder) the results were darker still.
However, on close examination of all the various colour matching options offered (including ICM matching to the sRGB colourspace) I found a quite distinctive problem with the DIVU conversion. DIVU obviously matches to the nearest colour whilst reducing the Gamut, but in so doing seems to be influenced by the colours around that colour. So for example grasses appeared greener, but when magnified and compared with an unconverted image it was obvious some of the more subtle colours had been lost in the conversion - many being changed to shades of the predominant green. This might initially look more vivid from a distance - but seemed to result in a ‘cast’ in some images and a slightly ‘unreal’ effect in other less colourful shots.
The original unconverted JPEG was certainly less vivid in comparison, but on closer examination offered the far more accurate and truthful rendition. Incidentally, experiments with increasing the saturation of the unconverted image in PSP (if you wanted a more vivid rendition) had far more accurate results than the DIVU conversion.
Of course this result is affected by the colourspace and Gamma of your monitor and taking off the PSP colour management resulted in a more washed out unconverted image and a slightly more acceptable (less dark but still colourcast) converted version.
As a further check I opened the unconverted image in a browser (to avoid PSP profiling) and likewise a converted JPEG (converted in DIVU sRGB ICC colour matching mode) and found the unconverted JPEG was absolutely colour identical in the browser as it was in the profiled PSP environment (probably because this is my default monitor profile as well actually - doh!) and the converted JPEG exhibited the same cast problems as it did within PSP colourspace.
So - my conclusions are - I personally won’t use DIVU to convert from the wider DiMAGE gamut to sRGB (or whatever I am using as a colourspace) as it doesn’t seem to offer best colour conversion in my opinion and under my controlled conditions. Although PSP obviously has to read in the gamut of the D7 JPEG as best it can (and probably discards the colours outside of the gamut of the profile installed) this still results in a more accurate colour rendition - as opposed to DIVU’s obvious trait of adding colours together to reduce the overall gamut - all interesting stuff.
A thought does occur - I wonder if Minolta originally intended DIVU to be used in colour matching mode to only deal with RAW images (as with colour matching off it doesn’t mess with JPEG colour at all and the images saved as TIFF are identical to unconverted JPEGs!). More information required obviously, still I hope this helps anyone who has got this far and like me was still unsure!
The general argument seems to go that colour matching the image produced by the D7 on your computer screen and comparing this with how you remember the original scene produces variable results - many of you seem to think using DIVU adds an incorrect colour balance to the image, and yet others, Minolta and some reviewers seem to think DIVU is indispensable in getting the D7 colour space (which is a wider gamut than typical) into what is a more standard and presumably more accurate rendition.
My D7 actually arrived with an extra slip of paper in the packing, obviously added after production and I quote from this “The DiMAGE7 utilises a wider colourspace than most consumer digital cameras. Part of this colourspace is created with information achieved from the CxProcess image processing system. To ensure that your images maintain faithful yet vivid colours it is preferable to use the Minolta Image Viewer Utility to acquire your images from the camera”
So I set about viewing a fairly varied set of images taken over the last few days with my D7 - in various colourspaces and with various options set (on a PC not MAC I’m afraid).
Images were taken at the typical ‘default’ highest JPEG (RAW imports into DIVU are another issue entirely!) quality and size - i.e. ‘Fine’ and ‘2560’.
As far as ‘converted’ images were concerned, these tests were performed loading images into DIVU:
1. With Colour Matching ‘on’
2. With various Output Colour Spaces as alternatives (including ICC profile matching)
3. Viewed both with and without Basic Colour Management enabled within PaintShop Pro 7
4. Saved as TIFF files (JPEG was avoided so as not to increase lossy compression with each save)
As far as ‘unconverted’ images were concerned, I simply dragged the images directly from the card untouched and dropped them into a folder entitled ‘un-converted’ for reference. Opening them directly in PSP for comparison.
Obviously certain criteria affect the outcome of these results and it is important that you have a level playing field for colour management to work. For instance, if you have no colour management options set within your image manipulation program then the results will be very different than if you use a colour management profile. Also how the image looks on the Web (browser rendered ) or on another monitor with different colourspace or profile is totally unpredictable (which is where I think most of the argument comes from). Also your monitor Gamma should be calibrated using what ever tools you have - I used the options within PSP 7.
So what did I find - well, in the event I found that all of the colour matching alternatives within DIVU resulted in darker and more colourful images than those that were unconverted. With colour management on in PSP and choosing the sRGB profile (installed by default in the windows/system/color folder) the results were darker still.
However, on close examination of all the various colour matching options offered (including ICM matching to the sRGB colourspace) I found a quite distinctive problem with the DIVU conversion. DIVU obviously matches to the nearest colour whilst reducing the Gamut, but in so doing seems to be influenced by the colours around that colour. So for example grasses appeared greener, but when magnified and compared with an unconverted image it was obvious some of the more subtle colours had been lost in the conversion - many being changed to shades of the predominant green. This might initially look more vivid from a distance - but seemed to result in a ‘cast’ in some images and a slightly ‘unreal’ effect in other less colourful shots.
The original unconverted JPEG was certainly less vivid in comparison, but on closer examination offered the far more accurate and truthful rendition. Incidentally, experiments with increasing the saturation of the unconverted image in PSP (if you wanted a more vivid rendition) had far more accurate results than the DIVU conversion.
Of course this result is affected by the colourspace and Gamma of your monitor and taking off the PSP colour management resulted in a more washed out unconverted image and a slightly more acceptable (less dark but still colourcast) converted version.
As a further check I opened the unconverted image in a browser (to avoid PSP profiling) and likewise a converted JPEG (converted in DIVU sRGB ICC colour matching mode) and found the unconverted JPEG was absolutely colour identical in the browser as it was in the profiled PSP environment (probably because this is my default monitor profile as well actually - doh!) and the converted JPEG exhibited the same cast problems as it did within PSP colourspace.
So - my conclusions are - I personally won’t use DIVU to convert from the wider DiMAGE gamut to sRGB (or whatever I am using as a colourspace) as it doesn’t seem to offer best colour conversion in my opinion and under my controlled conditions. Although PSP obviously has to read in the gamut of the D7 JPEG as best it can (and probably discards the colours outside of the gamut of the profile installed) this still results in a more accurate colour rendition - as opposed to DIVU’s obvious trait of adding colours together to reduce the overall gamut - all interesting stuff.
A thought does occur - I wonder if Minolta originally intended DIVU to be used in colour matching mode to only deal with RAW images (as with colour matching off it doesn’t mess with JPEG colour at all and the images saved as TIFF are identical to unconverted JPEGs!). More information required obviously, still I hope this helps anyone who has got this far and like me was still unsure!
