RAW?

What is the difference between say a RAW file and a BMP like you can edit in something as simple as MS Paint? Are the RAW files just proprietary uncompressed formats?

 

A BMP is an RGB image. A RAW file is not an image. It's a data file containing the brightness recorded by each pixel, the color of each pixel, and a list of the options you set.

So what's that do for you? No image processing is done in camera with RAW (well... they generally process the image with your settings for the default view and LCD view, but those aren't permanent). You have the freedom to set any of your camera options (except for exposure, a combination of ISO, Shutter Speed and Aperture) after the fact.

I find it's most useful with color balance. Unless you are in a studio, you'll walk from shade, to clouds, to sunlight, and everything in between while you are taking pictures. Who wants to go into the menus and change the white balance before every shot? Not I.

Can you change the color balance of a bitmap image? Sure. But not without quality loss.

 

Interesting, thanks for the explanation

 

Before I started shooting RAW, I had one episode where my white balance was majorly off. Had I shot those with RAW, I could have fixed them all no problem. From that point on, everything I take is RAW now. Post-processing can take a while, but you have much more flexibility. On most of the new cameras, you can take RAW+JPEG Fine, so if you don't need the RAW files, you can ditch them. If you do need them, they're there. Sorta like having your cake and eating it too

If you have Photoshop CS3, open a RAW file and see all of the options you have. You'll never go back.

 

So how do you go about getting a RAW file off of the memory card? I took pics at an event in RAW by accident, but when I insert the memory card into the computer, the files don't show up.

 

The advantages to RAW are that it contains pretty much all the information as the sensor was able to capture it. This lets you adjust white balance, color, brightness, contrast and so on. It also lets you convert to JPG with your own JPEG converter if you don't like the converter in the camera (not all JPEG converters are equal). JPG files can still be manipulated, but they will generally lose information when you do so and the results don't come out as well as if you start with RAW.

The disadvantages are that RAW takes a lot more space in the memory card and the hard disk and they take at least one more processing step before it gets to a stage that you would normally share them (JPG, TIF or BMP). If you use only RAW files, you need to have batch processing capability in your photo processing software, otherwise it gets pretty tedious.

Think negative (RAW) and prints (JPG) and you have the analogy to pre-digital work flow.

You generally need a RAW converter to read RAW files. This software can be provided by the camera manufacturer (RAW files are often proprietary, unless they are a type of RAW called DNG [digital negative] format) for free or fee. Also popular photo processing programs like Adobe Photoshop, Phase One Capture, and others have written RAW converters for the popular cameras/formats. If the files aren't showing up, then the file manager in the software you're using probably doesn't know about RAW files; but the files are still on the card (unless you erased or reformatted the card).

 

Guess I'm gonna bust out the manual for my camera and see if it will shoot in RAW+Jpg. I shoot a few hundred pics a week and the vast majority of those are not anything that would require anything beyond Jpg but there are occasions when I get a pic that it would be nice to be able to do something more with.

 

That's one of the things that deters me from using RAW.... what do you do in the long term with these files? Adjust them as necessary and then save as bmp or jpg? It seems like it would be pretty easy for them to end up as unopenable orphans in 10 years. I'm sure the JPEG format will some day be surpassed but it's standard enough that it should be easy enough to deal with them when that time comes.

 

Okay, so maybe I'm a little confused. When you say photo "info", are you referring to exif data? I'm not using CS3, I'm using the Nikon software that came with my D50. When I take the photos in RAW (nef. on Nikon)+JPEG, it appears that I'm getting all the same info with both files. The RAW files don't appear to give me any more info than the JPEGs.

When you edit RAW files, do you do it a different way than with JPEGs or do you edit them the same way with the only difference being quality loss?

EDIT: Oops, I just realized that those pics were converted from RAW files so I guess they are different that files that were originally taken as JPEGs.

 

noooooooo no no. Not exif. Maybe I didn't explain it well (I'm not much for teaching), so I'll try again.

Sensors in digital cameras don't take pictures. They just register how bright light hitting each pixel is. These pixels don't see color (excepting a new-fangled sensor in the Sigma digicams). So camera makers put color filters on top of each pixel that allow one and only one color of light in. Thus, some pixels will only see red light, some will only see blue light, and some (most) will only see green light.

Fake example: "Pixel 1 in row 1 sees green light and metered a brightness of 200. Pixel 2 in row 1 sees red light and metered a brightness of 112. ... The last pixel in last row sees only blue light and metered a brightness of 0."

That's not an image. That's just what the sensor records (think of it as a color/brightness map of the sensor)*. To make an image, that data must be processed (one of the main roles of the DIGIC processor in Canon cameras, if you are familiar). The computer takes all that information, adds to it some options (color balance, sharpness, etc.) and creates an RGB image, which generally takes the form of a JPEG or a TIFF.

*Said 'color/brightness map of the sensor' is recorded in a RAW file. ALL digital cameras shoot RAW. Not all digital cameras let you keep the RAW file. If you have a camera set to JPEG or TIFF, that RAW file will be temporary data that's automatically discarded after the image is processed.

 

I keep them along with the .xmp files from my processing. Alternately, I'll convert them to DNG.

I have a lot of hard drive space