HDR module question

[Cheman]

Hi Ivo
Could you explain about the noise suppression slider in the HDR module? Its default is 0%. How does this effect the noise reduction in the module itself and in the overall noise reduction when applied when tracking is turned off?
Always like reading your explanations
Che

[admin]

Hi Ivo
Could you explain about the noise suppression slider in the HDR module? Its default is 0%. How does this effect the noise reduction in the module itself and in the overall noise reduction when applied when tracking is turned off?
Always like reading your explanations
Che

Hmmm, yes. I just realised the current help text is actually quite unhelpful.
First off, you'll notice that the noise suppression slider is set to 100% by default when Tracking is off. This is because the noise suppression in HDR (in general) is not as good as leaving the noise suppression to the Denoise module w/Tracking on (because with Tracking on, we have a lot more data to work with).

The noise reduction in the HDR module measures the increase in entropy (for all intents and purposes 'the increase in detail') as a result of the HDR operation. It then proceeds to estimate for each pixel the portion of increased uncertainty (a measure of noise) that goes along with it. It then calculates a point spread function for each pixel that is proportional to the increase in entropy in such a way that noise remains the same between before- and after images. The result, in terms of visual appearance, is that noise remains constant between the two images, but any detail brought out may become somewhat 'blurred' (effectively blurring the noise along with it so that the increase in noise around 0%).

Tracking, however, can estimate the increase in uncertainty much more accurately without blurring too much detail. So it's best to leave the noise reduction to Denoise at the end of your flow when you switch Tracking off.

[Cheman]

thanks once again Ivo
Che