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M
matthewb35054952
Participant
April 12, 2019
Question

dng_validate and after stage 3

  • April 12, 2019
  • 1 reply
  • 2084 views

Hi Adobe,

I've read the SDK and have a DNG file I've created and have the following question:

I can use dng_validate with the "-3" option to output the de-bayered image and it looks as "it should" (meaning no noise, proper exposure).

But, if I let it continue past stage 3, the image is significantly brighter and consequently noisier.

My question is: what operation(s) happen after stage 3?

Cheers.

Matt

This topic has been closed for replies.

1 reply

S
sandy_mc
Inspiring
April 13, 2019

The best way to understand the difference between a stage three image and a final image is to tale a look in the SDK's dng_render_task code, which is what does most of the work.

But mostly it's the tone curve, look tables, huesatmap, some other adjustments such as baseline exposure. If you're looking at a simple DNG (one without tables), it's likely that most of the difference is the tone curve and the baseline exposure.

mattb65972029
mattb65972029
Participant
April 13, 2019

Excellent information! thank you!

I will review the SDK render function for better understanding.

For context: the images are from machine vision cameras(JAI) 8bit raw, so I do  it know the baseline exposure so the exif doesn’t include that ( and from what I understand dependent on the ISO which video cameras do not have ). I’ll check the tone curve. The linearization table is just linear.

Thank you!

matt

S
sandy_mc
Inspiring
April 13, 2019

FYI, generally for a CFA image, the DNG SDK will automatically add a default tone curve.

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