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Old Jul 30, 2006, 9:40 PM   #1
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Hi, I`m wondering if any one here can direct me to a websitewhere I can find out the basics of shooting, and processing, in RAW format? I`ve always just used JPEG but now I`m curious about using theRAW format. I`ve seen pics shot inRAW format and was really impressed with the rich colors in the photos.
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Old Aug 1, 2006, 6:42 PM   #2
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Look here:

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Old Aug 5, 2006, 7:57 PM   #3
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I've just read that review, and come away feeling dubious. E.g.:

Imagine that you want to make a modest adjustment to the file in Photoshop or any other editing program. Which would you rather have to work with, 47 levels or 384 levels? Clearly the 8 bit file will show posterization, which is the effect that one sees when instead of smooth transitions between brightness levels you see abrupt jumps.
Which sounds persuasive, except it's not the first RAW guide I've read which mentions that, and none of them actually include any examples of this supposed posturisation effect. I've shot thousands of JPEGS, and none that I could see show any abrupt jumps instead of smooth transitions inside gradients.

Nor does the higher dynamic range idea seem to hold much water: since, again, none of the guides seem to have done the actual experiment, I did my own, shooting the same picture of a very high dynamic range subject (the view of my desk including the view out of my window) in both RAW and JPEG. Some parts of the view through the window were overexposed in the JPEG, and those same parts were also overexposed in the RAW, no matter how I adjusted the settings in Adobe camera Raw. The RAW file didn't seem to hold any advantages in this area.

Then there's the white balance issue, which I still don't understand: all the guides seem to make out that once the image is converted into JPEG you can't adjust it any more, but Photoshop's white balance correction tools work perfectly well on JPEGs.

And if you don't want the camera to perform in-camera contrast, saturation, etc. on your images, you can turn it off in-camera. I haven't yet come across a camera that doesn't let you do this (though there are basic out-of-sensor adjustments that you can't turn off, these are usually applied to the RAW files as well - e.g. the low-level electron gain that is the digital equivalent of ISO speed).

Finally, there's the underlying issue that JPEGs have lossy compression and the niggling fear that image quality that's thrown away can never be brought back again. The thing is that if you shoot on your camera's highest quality setting, you'll be able to open and resave it at least a couple of times before visible compression artifacts start to appear (I think there was a Luminous landscape article that explored how many times you would need to do this at different quality levels before artifacts come in, but I can't find it at the moment). However, you of course only ever need to open and resave any file once, since you can keep the original out-of-camera JPEG and do any post-processing from that original file.

I think part of the issue might be that the guides are written by experienced photographers, who are used to shooting film before they switched to digital, and are taking the analogy or RAW to a 'digital negative' and JPEG to the final print a bit too far. They would never throw away the negatives when they make a print, so try to apply the same analogy to RAW files - except it isn't an exact (or, actually, a very good) analogy.

Of course, if anyone has come across a website or guide that actually *has* done the experiments and found RAW to be demonstrably superior, I would very much like to hear of it -- to an extent, I'm just playing devil's advocate here; I'm not by any means fundamentally opposed to RAW files, I'm just trying to question some of the same old edicts that seem to be layed out in all the explanations and guides without any accompanying evidence.

- Simon
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Old Aug 5, 2006, 8:50 PM   #4
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You're right that some of the things that can be done in RAW can also be done in programs like PS, although perhaps not with the same degree of precision or elan. White balance is one. Once white balance is fixed in Jpeg conversion, it's fixed, and what PS' "white balance" correction does is something else. A RAW converter's WB setting tool is entirely straightforward; you're actually changing the WB, not merely adjusting RBG and saturation values. I also agree that JPEGs taken at top settings allow for numerous resaves before any compression artifacts begin showing up.

What I like about RAW is mainly the ability to go back later and easily "redevelop the negative" from scratch, with different values from any previous development. And when I adjust the WB, I know I'm actually adjusting the WB, not merely the RGB values. Different RAW converters have different ways of handling color as well, which makes it important to get one that works well with your camera's kind of RAW files. Here's a recent example I posted to another forum regarding the highlight color controller in Silkypix:

. . .It is admittedly a bit difficult to see results in many cases, but there are occasions when it is a lifesaver. A quick shoot of a sleeping bee on a bush a few nights ago gave me some material to illustrate its usefullness.

First of all, Silkypix is a Japanese RAW developer that was ported to English by the Japanese themselves, so its English is pretty wonky; for example, the highlight controller menu has three sliders, named:

1. Saturation <-> Tone
2. Saturation <-> Hue
3. Restoration

However, at least one of these is seriously mislabeled. A better translation might be:

1. Chroma emphasis <-> Luminance emphasis

2. Saturation <-> Hue

3. Highlight Compensation (or Highlight Restoration)

With that much understood, the following is one of the frames I took the other night. I was shooting this with the Olympus E-300 + ED 50mm f2.0 macro; illumination was a hand-held flashlight (also necessary for focusing in the pitch black), and this frame came out seriously underexposed:

This is straight from the camera, all Silkypix controls at their default, so this is basically what a Jpeg from the camera would have looked like. The histogram's right side is about in the middle of the graph, so while all the highlight info is there, it isn't being used to advantage. So I raise the Silkypix EV to +1.0 to correct the overall underexposure, and get this:

Raising the exposure has overexposed several of the petals in the flower, resulting in washed out color. Here's where the highlight color controller comes in. I move the top slider "Saturation <-> Tone" (=Chroma emphasis <-> Luminance emphasis) fully to the left (0 = full chroma emphasis), and get this result:

Virtually all of the overexposure has been corrected, but the saturation is still too low, so now I move the 2nd slider ("Saturation <-> Hue") toward the left until I get a pleasant result; here, I move it from its center 128 position to the left until I get to 28, where I stop:

Despite the 1 stop overexposure in pp, the highlight controller has corrected for the excessive local luminance and loss in saturation. After using the other main controls to fine-tune the WB, overall contrast and color, I get the following final result (resized and sharpened in PS7):

The subject and picture aren't all that impressive, but I thought it made a good example of this technique.

This sort of adjustment might be possible in PS as well, but you'd be doing different things with the colors to achieve it.
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