Transformation Color Negative issue with 16 bit tif

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mark_hay
Posts: 28
Joined: August 22nd, 2009, 4:05 am

Transformation Color Negative issue with 16 bit tif

Post by mark_hay »

Hi, I found that if I use the Transformation Color Negative, I get a very blue output if the input file is a 16 bit tiff (made from a Raw photo of a colour negative.)

If I use an 8 bit tiff file for input, I get nicely colour balanced output.

(PWP 64 v 7.0.20 also behaves this way.)

Is this issue a bug?
thanks, Mark
jsachs
Posts: 4203
Joined: January 22nd, 2009, 11:03 pm

Re: Transformation Color Negative issue with 16 bit tif

Post by jsachs »

I tried to reproduce this by applying Color Negative to a 24-bit color negative image and the same image converted to 48-bit and got visually identical results using the default settings. Is is possible you clicked on the input image at some point and reset the black or white point accidentally?
Jonathan Sachs
Digital Light & Color
mark_hay
Posts: 28
Joined: August 22nd, 2009, 4:05 am

Re: Transformation Color Negative issue with 16 bit tif

Post by mark_hay »

Thanks Jonathan.
I tried again and this time was a bit more brutal with the Color Negative Transform gamma settings and got good output.

I also used one Raw file of the colour negative and used Canon DPP to convert to an 8 Bit Tif and 16 bit Tif.
I then used the PWP8 Color Negative Transform on each - having previously Reset the transformation.
As you found, I then got identical blue outputs.
Trying again with heavy handed changes to the gamma sliders, I got pleasantly balanced outputs.

If anything I learnt more about that Transform.

So no problem found I think.
Thanks, Mark
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