Bloom which lens

Because viewers have come to expect these effects, a rendered scene without them can appear very unnatural. There are several steps involved in the implementation of the light bloom effect. First, a copy of the rendered image is created. Then a bright pass filter is applied to this copy, emphasizing the bright areas of the image while de-emphasizing the dark areas.

After this, the image is converted into greyscale. In a perfect lens, the image is convolved according to an Airy disk. To approximate that effect, for a less-than-perfect lens, a Gaussian blur is used. Blend modes determine the way that two images will be combined when overlaid. Each pixel from the base image is combined mathematically with the pixel in the corresponding position in the overlay image.

Two blend modes are available for Unity image effects, Add and Screen. When the images are blended in Add mode, the values of the color channels red, green and blue are simply added together and clamped to the maximum value of 1.

Screen mode is so named because it simulates the effect of projecting the two source images onto a white screen simultaneously. Each color channel is combined separately but identically to the others. Firstly, the channel values of the two source pixels are inverted ie, subtracted from 1.

Then, the two inverted values are multiplied together and the result is inverted. The result is brighter than either of the two source pixels but it will be at maximum brightness only if one of the source colors was also. The overall effect is that more color variation and detail from the source images is preserved, leading to a gentler effect than Add mode. Legacy Documentation: Version 5. Language: English.

Unity Manual. Bloom Optimized. Publication 5. The method used to add bloom to the color buffer.