DCRaw displayed brighness differs from output

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dfmalan
Posts: 4
Joined: 01.02.2009 12:41
Location: Delft, The Netherlands

DCRaw displayed brighness differs from output

Unread postby dfmalan » 01.02.2009 13:14

I use Helicon Filter 4.92.2 Pro (MP), and have Nikon D80.

When using DCRaw to decode a relatively dark raw .NEF, the displayed image seems to be processed with a positive gamma curve (washed out). However, this is contradicted by the histogram. When I save the image it matches the histogram, and therefore looks very different (more contrasty) than the image seen during the workflow.

This makes it very difficult to edit, since it's not WYSIWYG. A solution is to first save as JPEG, and then open again. But this spoils the high-bit-depth pipeline and is clumsy.

Please see the attached picture, where the displayed image doesn't match the histogram. (no editing applied)

Any solution?

Regards, and thanks for a good product!
Francois
Attachments
Helicon_DCRaw.jpg
The image is a lot darker (see histogram) than displayed by HF. When saving this to output the output looks different - matching the histogram and not the live view.
Helicon_DCRaw.jpg (219.38 KiB) Viewed 3483 times

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Dan Kozub
Posts: 1157
Joined: 24.03.2004 18:14

Unread postby Dan Kozub » 04.02.2009 13:53

Francois,

This is strange indeed. I suspect that histogram may have been taken from the embedded thumbnail. Can you please upload the file for our test to http://heliconsoft.com/ftp.html?

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dfmalan
Posts: 4
Joined: 01.02.2009 12:41
Location: Delft, The Netherlands

Unread postby dfmalan » 04.02.2009 14:53

I uploaded the file as DSC_2453.NEF - thanks.

I should have mentioned that this *only* happens when using DCRaw, not with the embedded RAW converter or Adobe converter.

When saving the file (after using DCRaw) the output file looks like the histogram said it would, and like it looks when using the other RAW converters. Of course if I used the sliders to adjust the image to display like I want it the output file is totally underexposed.
Attachments
Adobe.jpg
The same Nikon RAW file, after conversion using Adobe RAW converter. Note that the brightness is now displayed correctly.
Adobe.jpg (214.31 KiB) Viewed 3456 times

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Dan Kozub
Posts: 1157
Joined: 24.03.2004 18:14

Unread postby Dan Kozub » 05.02.2009 13:30

This seems to be not a problem with histogram but a problem with non-linear convertion. Please try to disable "16 bit ..." option in DCRAW and use "-4" option in the field for additional command line parameters.


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