LDR / HDR - Workflow case F
From HDR input to HDR output
This case looks like a classic stitching of LDR images to get a LDR panorama, the difference being the HDR source which must remain HDR in output.
The source files are assumed to be produced by processing software to create the HDR.
Refer to High dynamic range imaging to learn what an HDR image is and how to produce it.
To achieve such a stitching is quite simple: disable the color correction and levels then use the power of the rendering engine with the Anti-ghost which can manage the HDR source files.
For this example, the source comes from the book The HDRI Handbook.
The jpeg source images were converted to HDR file with a software dedicated to this task.
So we have 8 .hdr format images in input.
The import of HDR files in autopano is just like with standard image files. However, these formats do not (usually) store metadata (Exif data for example).
Here, the data were lost, we must set this information to achieve the stitching.
An HDR image is also processed differently in several Autopano modules. When using the internal viewer of Autopano to display an HDR image, a new tab appears that allows to tonemap the preview image.
So, even if the source is high dynamic range, viewing of HDR images is possible using the internal editor.
This tonemapper menu applies to several areas on software: internal image viewer, fisheye circular crop editor, control points editor.
You can see it below in the fisheye circular crop editor:
To achieve such a stitching, you must disable the color correction. This can be done on the Group settings window, in Detection tab.
(Note: in autopano giga 3.0.x) you find this Detection tab in the Edit->Settings Menu and not in the Settings button of the Group Window!)
The Render settings are quite simple: Anti-ghost and HDR file format (.hdr or .exr (OpenEXR)). Do not use the HDR output profile because it is only useful for creating a HDR panorama from LDR sources files.
In this case, we already have the source in HDR.
Here is the rendering obtained in this example:
- Although this example suffers from a large ghost on the nadir image, it is completely and automatically removed on the render. There is no loss on the complete dynamics of the picture.
- The second screenshot is an illustration of tonemapping performed in a decicated software. We see that the stitching has met the dynamics while removing ghosts.