LDR / HDR - Workflow case E
From LDR input with bracketing to HDR output
In this example, 9 bracket levels have been made during the shooting.
When analyzing the source folder, Autopano discovers bracket stacks automatically.
Howvever, Autopano doesn't automatically group images by stack (depending on how the bracket function is implemented on your camera).
In this case, you must select the images in the group and use the contextual option "Create stack by N".
By default the reference image is the first image of the stack. In this example, the first image is too dark to find enough control points.
It requires to modify the index of the reference image via the "Create stack by N" option of the contextual menu:
The detection of the links can be computed by 2 different ways: through all bracket levels or level by level.
The shooting used here was performed with a tripod, each level bracket is identical to the previous (the 9 brackets of the same image are perfectly superimposed).
Autopano can then simply find links on the only reference level and to establish "hard links" (precisely superimposes an image stack without assigning control points).
In the Group settings, Detection tab, select the detection as follows, One stack level and Use hard links for a stack:
As the aim is to get a .hdr file in output, each bracket level must be balanced compared to the others.
Each image will provide consistent information with the others (similar radiance level not dependent on the shooting exposure).
In the Group settings, Panorama tab, uncheck the color correction by layer and select the type of correction: Exposure (best suited mode to bring all the images into the same HDR space).
Launch the detection, then edit the detected panorama.
Activation of the color correction in HDR mode can be done via the following menu:
tip: in this workflow (LDR to HDR), if color correction is disabled, exposure correction will not be estimated but directly computed from exif data.
The presence of many exposure levels allow to be more restrictive on the exposure's weight.
The curve of the Fusion tool allow to give more or less weight to pixels depending on their exposure.
Here, we will remove the over-exposed and under-exposed pixels (enable the fusion and remove the darkest and lightest parts):
In the HDR format, the dynamic is not limited, there is no need to reframe this dynamic.
Click on the Color anchors icon to disable the automatic levels histogram before to launch the color optimization.
Modify the Render settings to select the HDR output preset.
Do not forget to choose the HDR Radiance output format (.hdr).