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Re: 16 bit editing...

Good job Michael. That's closer to my expectations too.


> Mark,
> Thanks for posting. That's the first time I've witnessed anybody posting
> anything for examination when this topic comes up. I appreciate it.
> Now, in examining the images and their histograms, what I see is a lack of
> contrast in the 8 bit edited image relative to the 16 bit edited in the lower
> end. If the exact same curve adjustment operations were performed, I don't
> understand how this difference came about. Anyway, when I adjust the 8 bit
> image's curve lower end to closely match the 16 bit image curve's lower end,
> then the results are almost identicle.
> I've posted the 8 and 16 bit edited images that you posted untouced. I've also
> posted the adjusted (or corrected as I call it) 8 bit image. Alos, I've posted
> the 8 and 16 bit histograms along with the 8 bit corrected histogram. If you
> notice, the orginal 8 bit image has a relatively narrow range in the low end.
> Narrow ranges will ALWAYS lead to dull/flat looking images. The 16 bit and 8
> bit corrected ranges are pretty much the same and thus, the results are pretty
> much the same.
> Navigate to http://greeraa.com/albums/bit_depth/ to see.
> --- mrkeene@attbi.com wrote:
>> Mike,
>> Here is a real world comparison for you.
>> http://www.pbase.com/mark_kn/16bit_vs_8bit_editing
>> The image was taken with a Canon D60 in RAW mode and converted to a 16 bit
>> TIF.
>> A duplicate was made and converted to 8 bit.
>> An equal amount of levels were applied to both images.
>> The files were then resized to 640x480 for speed of loading and saved as JPG
>> quality 10.
>> No other manipulation was performed.
>> Download the images (they are ~80k each). Look at the original. Notice how
>> far
>> down in the shadows the lower portion of the image is. Now observe the
>> Johnson
>> grass in the lower right foreground on the 16 bit edited file compared with
>> the
>> 8 bit edited file. Draw you own conclusions.
>> Regards,
>> Mark K.

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