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Old Jun 17, 2019, 10:42 AM   #11
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Yes, OK, Thanks.
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JPEG images are constrained to 8-bit color. RAW Files contain 10, 12, sometimes even 14 bit color, but the process of working with all that data in order to create an image that can be displayed or printed will constrain that to quite a bit less. In truth, unless you've got something better than a conventional sRGB monitor and graphics adapter, working with RAW doesn't really buy you very much.
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Old Jun 17, 2019, 8:07 PM   #12
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Right, the raw data is what comes from the camera before any of the mentioned adjustments are performed. The things that affect the raw image are the camera controls for exposure, the lens, and any filters you use.
As TCav mentions, the raw data contains a lot more information than a jpeg, so (for example) the amount of detail in shadowed areas doesn't show as much in a single jpeg, but if you process the raw file, you can adjust the luminance curve to bring out the shadow details without multiple exposures.
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Old Jun 19, 2019, 10:19 PM   #13
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Right ..... OK.
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..... john
Quote:
Originally Posted by VTphotog View Post
Right, the raw data is what comes from the camera before any of the mentioned adjustments are performed. The things that affect the raw image are the camera controls for exposure, the lens, and any filters you use.
As TCav mentions, the raw data contains a lot more information than a jpeg, so (for example) the amount of detail in shadowed areas doesn't show as much in a single jpeg, but if you process the raw file, you can adjust the luminance curve to bring out the shadow details without multiple exposures.
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Old Jun 20, 2019, 3:08 PM   #14
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While RAW files do contain more data than JPEG files, the difference isn't great. RAW files contain the luminence values captured by the individual photoreceptors in an image sensor, each of which is under a color filter of the Bayer filter.



So while the luminance value for a photoreceptor under a green filter may contain a 12-bit value, that value is averaged with the values from other green photoreceptors in order to calculate green values for adjacent pixels under red and blue filters. So the precision of that 12-bit value is reduced to 10-bits or even less.

Plus, those RGB values are constrained further when an image is displayed on an 8-bit sRGB monitor.

Finally, the 8-bit values that you see on your screen are disassembled and reassembled when the image is printed on a CMYK printer further reducing their precision.

So again, RAW doesn't get you much except the ability to recover an image you REALLY screwed up. Fine tuning a properly exposed RAW image won't get you much more than you'd get from fine tuning the same image in a JPEG file.
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Last edited by TCav; Jun 22, 2019 at 4:47 PM.
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Old Jun 21, 2019, 5:25 PM   #15
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Thanks TCav.
...... john
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Old Jun 27, 2019, 12:56 PM   #16
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Hi again,
One of my cameras, a Kodak, has setting for sharpness (high, normal, and low), and settings for compression (fine, standard, and basic). Should 'fine' be the best compression setting (for jpgs)?
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Old Jun 27, 2019, 5:52 PM   #17
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Quote:
Originally Posted by Shinnen View Post
Hi again,
One of my cameras, a Kodak, has setting for sharpness (high, normal, and low), and settings for compression (fine, standard, and basic). Should 'fine' be the best compression setting (for jpgs)?
Thanks,
...... john
Absolutely.

And the setting for "Sharpness" is actually Acutance This doesn't actually change the sharpness, which is a unction of the resolution of the image sensor. It jjust alters the contrast on high contrast portions of the image. This may have the short term goal of making the image appear sharper at lower resolutions, but further processing will show the true effects, which are detrimental to image quality.
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Old Jun 28, 2019, 9:20 AM   #18
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Hi TCav,
That's interesting. I thought that compression was an indication of the degree of, well, compression; and that the higher the compression the more detail is lost (i. e. further from raw the image is); kind of like zipping a document.
.... john

Last edited by Shinnen; Jun 28, 2019 at 9:21 AM. Reason: remove redundancy
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Old Jun 28, 2019, 1:04 PM   #19
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Quote:
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That's interesting. I thought that compression was an indication of the degree of, well, compression; and that the higher the compression the more detail is lost (i. e. further from raw the image is); kind of like zipping a document.
It is. "Fine" is the least compressed (unless you've got an "Extra Fine" setting.) See https://en.wikipedia.org/wiki/JPEG#JPEG_compression

But, unlike Zip, the compression used in JPEG files is not lossless. So detail lost due to compression is permanent.

To be clear, in my previous response, I was mostly talking about the "Sharpness" setting, which has nothing to do with compression.
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Old Jun 28, 2019, 3:41 PM   #20
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Hi,
Thanks for the shortcul.
So then, 'fine' wrt to compression, does not mean more, it means less. That explains why the Fine compression is the largest file.
So, is 'raw' a term related to compression?
I have an old Sony V1 that allows me to save images as both TIF and JPG.
The TIF file is nearly 10 times the size of the JPG. Is TIF the forerunner of raw?
.... john
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