PDA

View Full Version : Photo editing with RAW vs High JPG...



diverdown
01-03-2005, 12:12 PM
I'm still looking to buy my first digital camera, but can't seem to find one with all the features I want. I like both Olympus C-7000 & the Sony P-150, with the Sony in the lead. The big determination now is the Sony dosnt save RAW files. As a scuba diver, I'd like to take underwater pictures, and I've heard that adjusting white balance in RAW helps adjust the color in varying depths.

My question is, can you not adjust the color/white balance on a high definition jpg at all? It seems like it can be done, but with some loss of quality, and if so, how much degredation can I expect? I do have Photoshop 7 on a Mac, so I have the tools if it can be done. (Im just not very good at using them yet :rolleyes: )

ktixx
01-03-2005, 12:36 PM
Basically the way I understand it, is that Raw is completely uncompressed. When you shoot in JPEG, if the pictures pixel color is purple, the the pixel is actually purple, but when you use RAW Instead of purple, the pixel on the picture has a little bit of blue in it and a little bit of red and gree is off. Therefore when you try and adjust the white balance, it is incredibly simple, because you can virtually retake the shot again just by using a program (usually supplied by the manufacturer) that will adjust the hues of the color. To relate that to real life use, when I shoot in raw, I tested my camera by taking some of the worst white balanced photo's immaginable, (they look red) but by using the software supplied by canon I can simply say I want to use a tungsoton balance, or I want to select a white object and use it to balance the white and the pictures end up being perfect. If you have the precious few seconds to properly adjust your camera BEFORE shooting, then RAW isn't necessary, but for those few times when you have a shot that you will never be able to take again and need to shoot quickly, RAW is the best way to go. As for your specific use, I am not a scuba diver and have never taken underwater pictures, so I really don't have any suggestions.

D70FAN
01-03-2005, 12:44 PM
Basically the way I understand it, is that Raw is completely uncompressed. When you shoot in JPEG, if the pictures pixel color is purple, the the pixel is actually purple, but when you use RAW Instead of purple, the pixel on the picture has a little bit of blue in it and a little bit of red and gree is off. Therefore when you try and adjust the white balance, it is incredibly simple, because you can virtually retake the shot again just by using a program (usually supplied by the manufacturer) that will adjust the hues of the color. To relate that to real life use, when I shoot in raw, I tested my camera by taking some of the worst white balanced photo's immaginable, (they look red) but by using the software supplied by canon I can simply say I want to use a tungsoton balance, or I want to select a white object and use it to balance the white and the pictures end up being perfect. If you have the precious few seconds to properly adjust your camera BEFORE shooting, then RAW isn't necessary, but for those few times when you have a shot that you will never be able to take again and need to shoot quickly, RAW is the best way to go. As for your specific use, I am not a scuba diver and have never taken underwater pictures, so I really don't have any suggestions.

Note: You can do white balance correction to JPEG's in Photoshop using available plug-ins. RAW file processing just takes it to the next step.

Note 2: Some/most RAW files are compressed but retain the original RGB values (lossless compression). That is why you can get a 5MB-8MB RAW file from a 6MP-8MP imager (18MP file)?

jaykinghorn
01-03-2005, 01:44 PM
All digital camera files orignate as raw files. That is to say, unprocessed data captured by the CCD. JPEGs are "processed" according to the white point specified by the camera's computer and the default contrast curves set by the camera. Raw files consist of the raw data along with an instruction set. The instruction set is written by the camera and contains some default information on what this raw data should look like. Using raw processing software, you can change the parameters of how the camera data should be processed by the software to change the white point, adjust contrast, tweak exposure and so forth. Raw files are a lot more powerful and a lot more flexible than JPEGs. Not only do you have the adjustment capability, but you also have the ability to export a file in 16-bits/channel for further editing, you can export the file in a number of different colorspaces and it is easier to make batch adjustments to a number of files.
As I'm sure you've found with your diving photos, your images are heavily saturated with blue that you will want to remove for the best results. Shooting raw gives you the capability to make a quick adjustment on the first file in the shoot to remove the blue cast, then apply that change to the rest of the images from your dive. To make a comparable change to JPEGs you would need to build an action to batch process the images. The amount of image degredation you encounter would be heavily dependent upon how much blue you were removing.
The disadvantages of shooting Raw are the need for larger CF cards and the need for Raw processing software(Photoshop 7 isn't really up to the task.But an upgrade to Photoshop 8 isn't that expensive).

I shoot exclusively Raw and most of the professional photographers I teach do as well. It gives you an unprecidented degree of flexibility and power to your digital photography.

Jay Kinghorn
RGB Imaging

diverdown
01-04-2005, 11:11 AM
Hmm.. looks like I really need to focus on RAW support, which puts me back to the drawing board on a camera. :mad: Guess I'm too picky, but to me $500+ is alot to spend and not get all the quality/features I'm looking for. I'm soo close on several, but nothing has it all yet.

Maybe Summer 2005 models will be better. :rolleyes:

Thanks for the information tho, it helped me understand the difference better.