RAW versus JPG:
DSLRs can be set to record images in JPEG (.jpg) files or RAW files, or both. Many new owners of DSLRs rightly wonder which one they should shoot. Well-known photo websites express a range of opinion on the subject of RAW vs JPG, with many enthusiasts and professionals preferring RAW. When I started shooting with a digital SLR, I shot primarily in JPEG, which I now regret. After a couple of years, I made a decision to switch to RAW.
Briefly, the difference between RAW files and JPG files boils down to preserving options. When you shoot in JPEG, the processor in the computer takes the RAW file information recorded by the camera and processes it to produce a finished image in the form of a .JPG file. The processing decisions are made based on instructions written into the software by the manufacturer, and by style settings chosen by the photographer.
These decisions made by the processor in the camera involve color, exposure, contrast, gamma, and more. They are irreversible, although many adjustments can be still made to the image in Photoshop.
Shooting in RAW vs JPG preserves all the information that the camera captures. The photographer, working at his computer, uses a RAW converter (a software program) to convert the RAW file to a JPG or a TIF. The original RAW file remains unchanged, and a new file is created. Thus, if the photographer doen't like the results of the conversion, he/she can reprocess with another set of settings without affecting the original image file.
Here are some examples, all from the same exposure - one click of the shutter. The camera was set to record RAW plus JPG:
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1) Above is the RAW file, converted to JPG in DxO Optics Pro without any adjustments whatsoever. By the way, this was the best exposure of a 3-shot bracket. It was shot at -1 stop below the indicated exposure to hold highlight detail in the grass.
2) Here is the in-camera conversion done to the exact same image by the well-regarded Digic III processor in my Canon X1i. The processor decided to compensate for all the dark information in the center of the photo by brightening the exposure, but that resulted in grass that is too bright and an overall washed-out look. The histogram in the LCD on the camera showed the highlight detail well inside the right side of the graph.
The brightening brought out detail in the dark end of the barn, which is a good thing. The image could be improved in Photoshop, but not all the detail and color in the grass would be recovered.
3) Here is the same shot again, this time converted in DxO Optics Pro, with adjustments. I adusted the white balance to warm the image a little, and I boosted the gamma to open up the shadows.
4) Here is the same shot one last time. Here I've warmed it a little bit more, and opened up the shadows a little more. This is arguably the most realistic conversion, as the sun was low and the light was quite warm, but I prefer the previous conversion.
