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LDR / HDR : How it works


It is always very complicated to talk about HDR photography because that term has too many meanings (is it a picture, is it a production line, is it a tool? etc ...).
In our case, we'll be talking about what we have in input (images) and what we want in output (one or more panoramas).

First, a quick contextual definition of LDR and HDR:

  • LDR files : refers to a low dynamic range image format (LDR) : *.jpeg, *.tiff, *.RAW, etc...
  • HDR files : refers to a high dynamic range image format (HDR) : *.hdr or *.exr (OpenExr).

We are now going to look at every I/O possible case: LDR or HDR source images into HDR or LDR panoramas.

Depending on the input data's type, here is a quick overview of the color correction settings and rendering profiles to use:

In input, my files are... In output, I want to get a panorama...
LDR (jpeg, tiff, raw) LDR Color correction Autopano 250 editoricon color auto.png
Anti-ghost render

Workflow case A
HDR Color correction (1) Autopano 250 editoricon color hdr.png
Anti-ghost render

Workflow case D
LDR (jpeg, tiff, raw)
+ bracketing (several exposure per position)
LDR Color correction by layers Autopano 250 editoricon color auto.png
Exposure Fusion render

Workflow case B
Global HDR Color correction (1) Autopano 250 editoricon color hdr.png
HDR Output render

Workflow case E
HDR (HDR, OpenEXR) No tonemapper in Autopano
so not completely supported
No Color correction Autopano 250 editoricon color none.png
Anti-ghost render

Workflow case F

Note :
It may be noticed that generally, a LDR correction is required when we want LDR output and a HDR correction to get HDR output.
However, these parameters are not automated because some cases require to not meet this consistency.

(1) The Feature "HDR Color correction" is dependent on the EXIF data like shutter speed and fnumber. Is this information missing than the "HDR Color correction" remains disabled.
source: http://www.kolor.com/forum/p109985-today-09-46-15#p109985

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