"Imaging" collectively refers to the process of converting Indigo's internal physical light data into a normal RGB image which can be displayed on a computer screen.
The following image shows the fully expanded Imaging view; we'll cover with numbered sections sequentially:
Here you can set the width and height of the image Indigo will render, along with the image super-sampling factor. The aspect ratio (ratio of image width to height) can be kept constant while editing either field by checking the "Lock aspect ratio" option.
If the super-sampling factor is greater than 1, then the image is rendered at a higher resolution internally and down-sampled before the render is displayed on-screen or saved to disk. This can help to reduce aliasing around high contrast edges and produce a sharper final image. Note that higher factors require a lot more memory (RAM), which scales by the square of the super-sampling factor: with a factor of 2, it will use 4x as much memory, with a factor of 3 it will use 9x as much, etc.
Aperture diffraction causes small bright light sources to "bloom" (diffract) through the simulated camera's aperture, creating a distinctive rainbow-coloured glow.
The exact shape of the diffraction pattern depends on the scene's aperture shape and obstacle map. For more information please see the camera documentation.
Tone mapping is the process whereby the high dynamic range (HDR) image internally stored by Indigo is converted to a low dynamic range (LDR) image for display on a normal computer screen.
This form of range compression is necessary because in real life, the sun is many thousands of times brighter than a dimly lit room, however on a standard computer screen we can only perceive approximately 200 brightness levels.
- Reinhard: The default "auto-exposure" mode, which handles images with very high dynamic range well, but can have lower contrast than the other modes.
- Camera: This mode allows you to select from a number of pre-defined camera response profiles, which accurately model the response of the camera's optics for various manufacturers and camera models.
- Linear: This mode is the simplest of all, providing only a linear scaling (or gain) factor and providing no dynamic range compression.
- Filmic: Like Linear, this tone mapper has only one control, but it responds quite differently with significantly less contrast at high brightness (Scale) values.
A white point (aka "reference white") is a colour which serves to define what "white" should look like in image. This is related to the human vision system's adaptation to different colour temperatures, and allows you to change how "warm" or "cold" an image appears.
This section shows a histogram of the colours present in the image, which is useful to analyse the imaging settings for over-exposure or under-exposure.