how do you display 16 bit info on 16 bit images?

W
Posted By
winhag
Jul 25, 2004
Views
827
Replies
5
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Closed
Folks,

Question. When I work on 16 bit images, all curves info etc. still display as if the image is an 8 bit image. (Photoshop CS on Windows XP). Is there a way to have the various data displays show as 16 bit values (i.e. 0-65536 vs. 0-255)??

Thanks

W
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Bart van der Wolf
Jul 25, 2004
"WD" wrote in message
Folks,

Question. When I work on 16 bit images, all curves info etc. still display as if the image is an 8 bit image. (Photoshop CS on Windows
XP).
Is there a way to have the various data displays show as 16 bit values (i.e. 0-65536 vs. 0-255)??

Select options of Window|info palette, tick "Show 16 bit values".

Bart
W
winhag
Jul 26, 2004
Bart,

Thanks. That worked for ‘info’. Is there anything that can be done regarding curves or histograms?

Also, the max value is 32768 and not 65536, do you know the reason for this?

Thanks again

W

"Bart van der Wolf" …
"WD" wrote in message
Folks,

Question. When I work on 16 bit images, all curves info etc. still display as if the image is an 8 bit image. (Photoshop CS on Windows
XP).
Is there a way to have the various data displays show as 16 bit values (i.e. 0-65536 vs. 0-255)??

Select options of Window|info palette, tick "Show 16 bit values".
Bart
MR
Mike Russell
Jul 26, 2004
WD wrote:
Bart,

Thanks. That worked for ‘info’. Is there anything that can be done regarding curves or histograms?

Also, the max value is 32768 and not 65536, do you know the reason for this?

Photoshop’s 16 bit format ranges from 0 to 0x8000, using just one value more than 15 bits. The remaining values are not used. Just a guess, but perhaps they are used for intermediate values in image calculations.

I’ve considered adding 16 bit display to Curvemeister. It’s a reasonable request, but there has been no request for it.
—

Mike Russell
www.geigy.2y.net
BV
Bart van der Wolf
Jul 26, 2004
"WD" wrote in message
Bart,

Thanks. That worked for ‘info’. Is there anything that can be done regarding curves or histograms?

Not with a Photoshop setting, but there is a free histogram "filter" available at:
http://www.reindeergraphics.com/free.shtml#widehisto
It also shows that to display (and select ranges) more than 256 values, one needs a wide histogram to really benefit. Curves are too crude to need 15-bit precision, you’ll need a different application if you need that type of accuracy.

Also, the max value is 32768 and not 65536, do you know the reason
for this?

That’s how it is in Photoshop. The final high bit is used for calculation overflow. It allows calculations (including rounding and multiplications) to be done with 16-bit integer math, which is presumably quicker in most processors than 32-bit math (or you could do 2 multiplications at the same time).

Bart
X
Xalinai
Jul 26, 2004
WD wrote:

Bart,

Thanks. That worked for ‘info’. Is there anything that can be done regarding curves or histograms?

Also, the max value is 32768 and not 65536, do you know the reason for this?

The reason ist that you are working with Photoshop.

According to the PS gurus here this is not a bug but PS works as designed.

They didn’t mention why there is no limit of 128 in the eight-bit version. 🙂

Michael

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