Floyd L. Davidson
bd <bdebreil@teaser.fr>wrote:

bd
[...] DCRAW works fine, but... the results are not as good looking as those that the camera delivers in jpg format, since, I suppose, the latter go through one or more enhancement processes such as sharpening, improving contours and contrasts through the use of various filters or in altering gamma factor etc..

Floyd L. Davidson
There are many things that are simply impossible (sharpening) or difficult (any adjustment that isn't automatic) with DCRAW. It is not meant to be used as a general tool.

bd
With my new EOS 600D, I use "ufraw", which works as an interface for dcraw. The results that I obtain are neither better nor worse than those with the G2.

Floyd L. Davidson
Note that UFRAW is a lot more than and "interface" using DCRAW. It uses DCRAW as the basic converter engine, but has it's own processing for many other of the enhancement tools you need.

However, it is a RAW converter, not an image editor. Hence there is more to post processing that it can do alone! The next step is to process each image with GIMP.

This is certain to get a bit lengthy, but let me walk you through some suggestions for your workflow.

First, you want UFRAW to set a "base" configuration that you start with. That's a little complex because when working you want it to save all setting each time you save an image. When you start work on a group of files, the first thing is to check the configuration of UFRAW. Here are my defaults, from top to bottom:

---- Pre-Configuration ----

At the top: Enable Raw histogram

2nd line: Set Exposure to 0.0 (see Note) Set Restore Details for Negative EV to "HSV space for sharp detail" Set Clip Highlights for Positive EV to "digital linear" Set Auto Adjust Exposure to disabled (see Note) Note: Clicking the last icon will set exposure to 0 and disable Auto Adjust.

3rd line: White Balance -- set to either "auto" or "camera" Grayscale Mode -- None (which means color) Lens correction (optional, may not exist) -- None Base Curve -- Straight Line (use reset button on right) Color Management -- A. Input ICC Profile: No profile B. Gamma: 0.45 C. Linearity: 0.10 D. Output ICC Profile: sRGB E. Output intent: Perceptual F. Output Depth: 8 (16 sometimes) G. Display ICC Profile: sRGB H. Display intent: Perceptual Correct Luminosity, Saturation -- A. Contrast (Optional, may not exist): 1.00 B. Saturation: 1.30 C. Manual curve D. Click on both left and right bottom reset buttons Lightness Adjustments -- Does nothing on mine (if it exists, set everything to 0) Crop and Rotate -- Click on two reset buttons, and "lock" icon. Note that there are bugs associated with the functions in this menu, and on occasion odd crops may show up that require these resets to be reset to get a normal view.

Save -- THIS IS IMPORTANT! A. The "path" should be your current working directory. B. Select the output file format (I would recommend only TIFF). C. Set JPEG compression level as desired (less than 92) C. Enable JPEG progressive encoding D. Enable TIFF lossless compression E. Enable Embed EXIF F. ** Set Create ID file to ONLY ** G. Set save image defaults to Always H. Disable remembering output path I. Enable overwriting files without asking

Bottom of page: Enable Live Histogram Check the indicate box for Overexposure Uncheck the indicate box for Underexposure

---- End of Pre-Configuration ----

Obviously there are some items you might want to set differently. I would suggest waiting until you work with those for awhile first, and then slowly start changing things to match your specific needs *after* you get an idea what the purpose is for each. However, it is also true that sometimes you'll want something different for a specific set of images, so if it actually makes a difference, change the default on a case by case basis.

The effect of setting UFRAW to only write an "ID" file is important. I start UFRAW like this:

bd
ufraw *.nef

Floyd L. Davidson
You will want to change *.nef to whatever suffix is appropriate for your raw files. But it will do each raw file in sequence. If you don't want to do a given file, click on "cancel" instead of "save" and it will skip to the next file. Clicking on "save" will *only* write a *.ufraw file, which happens almost instantly. It then goes to the next RAW file. You don't need to wait for it to convert each file.

When you've gone through all of the files you want to process, convert them to TIFF format files with a batch process like this:

bd
ufraw-batch *.ufraw

Floyd L. Davidson
You can then take a coffee break, read Usenet, or whatever while all of the time consuming number crunching is done.

But lets go back to the first RAW file you process, and follow a typical sequence for making the adjustments. I usually just put the exposure slider somewhere near correct, and then adjust White Balance. You can switch between different presets, or go to manual and adjust it yourself. Then I click the "Color management" icon and adjust gamma and linearity plus exposure to get the look I want. If the image is going to be processed by GIMP, leave the output bit depth at 8. If you will process with software that can deal with 16 bits, change it to that.

The next step will be processing with an editor. If you use GIMP or any other 8 bit editor you'll want to get the gamma and brightness very close to perfect with UFRAW, because changing either in GIMP can cause posterization. But GIMP is fine for cropping and most other edits. You can do minor adjustments to contrast and brightness, in particular to local area selections. Local sharpening and blurring is also done with GIMP, and then before writing the final output file to disk it should be 1) saved as an XCF formatted intermediate file, 2) scaled to the appropriate size, 3) apply Sharpen and Unsharp Mask, and finally 4) saved to disk (perhaps as a JPEG format).

Your first efforts may not match the perceived quality of images produced by the cameras JPEG engine, but... rest assured that with practice you can develop the skills needed to always produce a better result than the camera does. The reason is fairly simple too. Your computer can at least equal what the camera's computer can do, but it has the advantage of 20-20 hind sight too. The camera has to be configured before you make an exposure. You only get one guess at what is right for each exposure, and that's it. With post processing you take the exact same raw sensor data the camera used, but you get to try any and every possible variation on configuration until you get not just something close, but rather the precise configuration you like the best. Many times every single shot is slightly different, and you do get better results for each one!

Just don't expect to do that immediately, and do expect to save your raw files because I guarantee that in 2 years, not to mention 5 years, you'll be better at editing!

Also be aware that with Linux if you become proficient at writing shell scripts there is just no end of ways to improve productivity. The ImageMagick tools are fabulous for editing. And there are many ways a shell script can speed up your workflow. For example, I preview my images, as JPEGs, with a very customized version of XV which can sort them into various directories. The JPEG images I don't want to convert with UFRAW go into one special directory, and then a shell script moves the RAW files to the same directories where the JPEG is now at. Then I run UFRAW and it never loads a file I don't want to process. Plus when I want to run the batch on all of them, I use a script that does odd things like automatically setting wavelet noise reduction depending on the ISO it was shot at, and it determines how many CPU cores are available and proceeds to keep each CPU busy with a different process (which with as many as 12 cores can make a huge difference in how fast a few hundred RAW files can be converted to TIFF files).