HDR Tone mapping and vacation i sharp sunlight

(Olaf Berthelsen) #1

After a short vacation in Piemonte with lots of sharp sunlight and deep shadows I must say that it is a real pleasure to have RT as a travel companion:

After a day in the sun I copy the photos to my pc, start RT in batch mode using the CLI interface, take a cup of coffee, and examine the photos developed utilizing my dynamic profile. My dynamic profile is set up to select an auto matched profile depending on the photos ISO setting and enhanced by some small adjustments. Many photos just need some minor adjustments especially using the excellent HDR tone mapping tool.

Unfortunately there is yet no HDR documentation in rawpedia. I understand the function of the sliders as follows:

Anchor decides the lightness middle point used for deciding which part of the image is considered highlights and shadows. So if the anchor point is increased then the whole image becomes lighter because a bigger part of the image is considered to be shadows and vice versa.

Amount controls how strong the effect is. In other words how much the shadows and highlights are tone mapped (compressed).

Threshold controls how far away from the anchor point the tone mapping takes place thus a higher threshold value increases the contrast in the image compared to a lower threshold value.

(Morgan Hardwood) #2

“Amount” is “beta”, “threshold” is “alpha”:

(Olaf Berthelsen) #3

Thank you for your response.

I have used the HDR tool to recover highlights and deep shadows in pictures taken I sharp sunlight. In such pictures both highlights and shadows seem to be exaggerated compared to the human vision. According to the references you send to me the HDR tool can do just that and more because the tool is of more general nature. So my attempt to explain the sliders is no good.

I was hoping for a simple guide to how and when to use the HDR-tone mapping tool just like the straight forward rawpedia explanations covering the other tools.