Linear profile editing - better than USM, raw file support

Hi All!

(Hope this isn't too geeky )

In playing around with PEF file conversion using dcRAW which can create 16-bit linear space Photoshop files, I've discovered some more very, very interesting things.

Here's what you do: convert an image to linear space, perform USM within that colour space, then convert to the target colour space.

Even better, use the linear output from dcRAW to begin with

And. even better, use the blur-then-sharpen technique on the www.aim-dtp.net web page.

Here are the steps:
1. Download Linear colour space profiles: http://www.aim-dtp.net/aim/download/aim_profiles.zip
2. Unzip these, and copy to C:WINDOWSSYSTEM32COLOR
3. When opening a JPG, assign it the appropriate profile first: either sRGB or AdobeRGB. Then, using the "Image | Mode | Convert to profile" menu assign it the colour profile "AIM RGB Pro = WideGamut D65 G1.00" or the "AIM RGB = Trinitron D65 G1.00" - Gamma 1.00 means linear colour. If you are loading a PSD file from dcRAW, just assign this on loading.
4. Try doing a really heavy USM, say 500% at 0.5 radius, 0 threshold. Looks great!
5. Undo that, and download this zip: http://www.aim-dtp.net/aim/techniques/usm/blur_sharpen.zip
6. Extract it into its own directory
7. Use Filter | Other | Custom and load "Blurr 030%.acf". Apply it
8. Use Filter | Other | Custom and load "Sharpen 500%.acf". Apply it
9. Now use the Image | Mode | Convert to Profile to assign to sRGB or AdobeRGB

Well, it sounds complicated, but it 'aint
The results just blow me away - I have injected some life into a slightly dull shot and given it some real "pazzaz"!

If you want to do some further reading, check out www.aim-dtp.net - it is tricky finding your way around, but the results are worth it

(And there is this: http://www.aim-dtp.net/aim/calibration/xlprofiler/ for building ICC profiles)

Let me know how you get on, and enjoy!!
Matt

I have actually learnt my lesson while creating a lot of thumbnails. One obvious example is here:

http://www.lbodnar.dsl.pipex.com/imaging/thumb.html

Notice how "ordinary" thumbnail cries for sharpening while "proper" one is sharp straight after downscaling.

I am using ImageMagick for batch processing. It has all I need - 16 bit processing, image manipulation, conversion, etc and it is free.

Ibodnar,

Thanks for the comparison images, and especially the link to ImageMagick - I am checking it out

BTW, Did you get the second example the wrong way around?? You said the left one was linear converted, but that's the one that does not show the graduated colours :

Matt

Matt,
that original calibration chart should have no colour cast on properly calibrated system with gamma 2.5 and so the thumbnail downsacled linearly with gamma correction 2.5 removed. Also there should be no ramp on the gray scale.

Since the calibration chart has been designed for gamma 2.5 system then removing exactly that correction and averaging (downscaling) shows how it should look on ideal system with gamma 2.5.

If your system is calibrated to gamma 2.2 then please look up the proper chart from AIM-DTP site.

Thanks for that - yes my LCD is at gamma 2.2

Should have read it more carefully

Matt