RAW vs. JPEG

Started Feb 10, 2013 | Discussions thread
GreenMountainGirl Contributing Member • Posts: 684
Re: Starting with RAW Chicken...

Leonard Migliore wrote:

GreenMountainGirl wrote:

So explain about the rules for making a JPEG from RAW. I use the editing functions of the program to come up with an effect that I find pleasing, but would really like to get better so that I can make the images come closer to outstanding!

There's two sets of rules. One is for making an image out of a RAW file, the other is for compressing this image as a JPEG. The rules are completely unconnected. To make an image out of a RAW file, the software must know what each photosite is seeing. ... The first thing the RAW converter does, sometimes, is to virtually shift each set of photosites to correct for chromatic aberration. Then it looks at the colors surrounding each photosite and decides what color to make each pixel...

This helps explain why some photographers will edit at the pixel level!

Lightroom hides these details and gives you controls like brightness, contrast, vibrance and tons of others. When you adjust these, the software tweaks the brightness of each displayed pixel in different clever ways. Sometimes you can hear the steam coming out of your computer while this is going on (no, not really).

Thank goodness!  I would be supremely overwhelmed if LR did not do all this for me.  Maybe later I will be ready for pixel-level editing!

None of this has anything to do with making a JPEG; it's just a bunch of ways to alter the displayed image. Once you have something on your monitor you like, you can save it as a TIFF, which just records the RGB values of each pixel, or as a JPEG, which applies a set of compression rules to make a much smaller file that looks a lot like the original. With JPEG's, you can vary the compression, so you have control over the final file size. But, unsurprisingly, if you compress the file a lot, it looks worse when you expand it again.

I have wondered why there are so many different ways to save an image file.  At my stage, RAW seems like the best, because I understand that one best (not completely!).  As for JPEG, I have experienced the worsening of images from when I first started, taking pictures only in JPEG because my Elements 9 would not read the RAW files produced by my D7000.  Editing was a bit of a nightmare!

As for understanding the technical aspect of RAW, I do appreciate the explanations of this, and I think it will help in the long run as I work on getting better photographs.  The best part is, now I understand more than I did before thanks to your explanations (and the explanations of others, too).

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GreenMountainGirl

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