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Old Feb 18, 2006, 10:04 AM   #11
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In the initial capture, you don't take any loss. It is the very process of constantly opening and closing jpeg format photos that creates degrading.

There is the argument that a raw image has the potential for capturing a mathematically, or measurably higher dynamic range than a jpeg. But I believe that might also be a component of very complex lighting.

I plan to work more with RAW images and see more of what greater experience can teach me..

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Old Feb 18, 2006, 10:16 AM   #12
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mtclimber wrote:

In the initial capture, you don't take any loss.

That goes against my understanding of the process but, given theversatility of digital electronics, anything can be done.

Maybe I'll pose the questionelsewhere and maybe attractMike O'Brien.

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Old Feb 18, 2006, 11:18 AM   #13
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I shoot in RAW with the p850 frequently. The reason your not seeing an image posted is (asw an example) the Raw image is 8,716KB vs 790KB for the .jpg. In order to send some one the RAW image the guy would probably save it in jpg and squirrel the whole comparison.

I like RAW for shots that are important. ie Bride&Groom posed shot. Then bring them into Photoshop. There is a differience in quality, evan though it is slight, There is better dynamic range and sharpness.

The camera, by the way, takes the RAW image from the sensor and converts it to .JPG and yes, there will be slight losses in that initial conversion. No matter what camera or what .jpg conversion program. Note the word SLIGHT.

And as far as .jpg goes or any lossy format. Additional losses only occur if you "open the .jpg - perform some type of change - and then resave it" there is no loss from just opening it, viewing it, and then closing it.

Hope this helps, ever so slightly


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Old Feb 19, 2006, 9:06 AM   #14
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I couldn't have explained it more eloquently than TheGreyGeek. Let me recommend a good book called Adobe Camera Raw For Digital Photographers Only, by Rob Sheppard. You can probably find it in your local public library (remember those?).
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Old Feb 23, 2006, 8:08 PM   #15
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mtclimber wrote:
In the initial capture, you don't take any loss. It is the very process of constantly opening and closing jpeg format photos that creates degrading.
Actually there is a loss, two losses to be precise. The CCD captures a 12-bit per channel image and a Jpeg file only supports 8-bits per channel. Also the jpeg alogrithim throws out data so you loose a little more.

For most pictures you won't notice this loss, but for scenes with a lot of dynamic range you will get better results shooting in RAW format.
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Old Feb 23, 2006, 8:42 PM   #16
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For the maximum potential quality, shoot in raw. That's unprocessed information from your sensor (it's been converted to digital via the analog to digital converter, but nothing else has been done to it other than adding some metadata to the files that converters and browsers can use).

If you shoot in jpeg or tiff, then the camera has already processed the image (demosaic algorithms, adjusted sharpening, contrast, saturation, white balance, etc.).

There are a variety of tools available to process raw images, and these tools are continuing to improve. You'll also find major differences in the way different raw converters approach converting images from raw (and improvements are being made all the time).

So, you may be able to reprocess cherished images later as advances are made with even better tools.

If you shoot in jpeg or tiff, it's too late (the image as already been processed by the camera). Sure, you can make adjustments to a jpeg file, to a point. But, you're working with 8 bits per channel versus 16 bits per channel, and the demosaic process has already been performed. So, you're not going to extract any detail that was destroyed by the camera's processing of the data from the sensor.

Is it that important to shoot in raw? Probably not to most users.

The speed of the camera impacts how practical it is to shoot that way. With most camera models, it can be more trouble than it's worth (just because of the increased time to write the images to media).

I've started shooting almost exclusively in raw with a Maxxum 5D I've got now. But, it can write to media at about 1 frame per second with a fast card shooting in raw, after it's buffer is full. So, it's not as big of a performance penalty to shoot that way (for the type of shooting I normally do).

I'd rather have a powerful computer converting the images from raw using advanced algorithms, versus the camera trying to do it in a split second.

For someone shooting sports or needing a faster frame rate, then jpeg would be more practical.

Of course, you've also got an extra step (or steps if you want to further enhance the images after they're converted) involved if you shoot raw. That takes time and many camera owners may not want to mess with it.

Kodak's algorithms are usually designed for rather "punchy" images straight from the camera, with more saturation and contrast than you typically find (although newer models are starting to do more neutral processing for better retention of detail). Chances are, their raw converter is using similar algorithms.

That's good for most purposes and requires the least amount of post processing. But, it can destroy detail from too much contrast and sharpening. Noise reduction algorithms in the image processing pipeline will also tend to smooth out detail as ISO speeds are increased.

If you process the raw files using something like Adobe Camera Raw, you'll get more neutral results with more real detail and less smoothing of detail from noise reduction.

To the untrained eye, they may not look as sharp (or rich in color and saturation), and noise may look worse.

But, you'll have more real detail to work with in post processing, applying as little or as much noise reduction as desired for the amount of detail you want to retain using available 3rd party tools. Ditto for sharpening, contrast, etc.

So, there are pros and cons to any approach.

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Old Feb 23, 2006, 9:51 PM   #17
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Again, JimC summed it up totally, accurately and objectively. Personally, I don't need to use RAW to shoot a mundane picture of a house for a magazine, I usually only need to make the smallest of adjustments to the original JPEGs, then I save the pics as TIFFs, making my magazine printer happy and leaving the original JPEG unaltered. Even when shooting a multi-million dollar estate, we won't use RAW, but we WILL use a very good DSLR!
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