Bloom and Lens Flares

Blooming is the optical effect where light from a bright source (such as a glint) appears to leak into surrounding objects. The Bloom and Lens Flares image effect adds bloom and also automatically generates lens flares in a highly efficient way. Bloom is a very distinctive effect that can make a big difference to a scene and may suggest a magical or dreamlike environment especially when used in conjunction with HDR rendering. Bloom and Lens Flares is actually an enhanced version of the Glow image effect which offers greater control over the bloom at the expense of rendering performance.

As with the other image effects, this effect is only available in Unity Pro and you must have the Pro Standard Assets installed before it becomes available.

Properties

Tweak Mode	Choose complex mode for additional options such as lens flares.
Blend mode	The method used to add bloom to the color buffer. The softer Screen mode is better for preserving bright image details but doesn't work with HDR.
HDR	Whether bloom is using HDR buffers. This will result in a different look as pixel intensities may leave the [0,1] range, see details in tonemapping and HDR.
Cast lens flares	Enable or disable automatic lens flare generation.

Intensity	The global light intensity of the added light (affects bloom and lens flares).
Threshhold	Regions of the image brighter than this threshold receive blooming (and potentially lens flares).
Blur iterations	The number of times gaussian blur is applied. More iterations improve smoothness but take extra time to process and hide small frequencies.
Blur spread	The max radius of the blur. Does not affect performance.
Use alpha mask	The degree to which the alpha channel acts as a mask for the bloom effect.

Lens flare mode	The type of lens flare. The options are Ghosting, Anamorphic or a mix of the two.
Lens flare mask	Mask used to prevent lens flare artifacts at screen edges.
Local intensity	Local intensity used only for lens flares.
Local threshold	The accumulative light intensity threshold that defines which image parts are candidates for lens flares.
Stretch width	The width for anamorphic lens flares.
Blur iterations	The number of times blurring is applied to anamorphic lens flares. More iterations improve smoothness but take more processing time.
Tint Color	Color modulation for the anamorphic flare type.
1st-4th Color	Color modulation for all lens flares when Ghosting or Combined is chosen.

Blend Modes: Add and Screen

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.

Add Mode

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. The overall effect is that areas of each image that aren't especially bright can easily blend to maximum brightness in the result. The final image tends to lose color and detail and so Add mode is useful when a dazzling "white out" effect is required.

Screen Mode

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.

Hardware support

This effect requires a graphics card with pixel shaders (2.0) or OpenGL ES 2.0. PC: NVIDIA cards since 2003 (GeForce FX), AMD cards since 2004 (Radeon 9500), Intel cards since 2005 (GMA 900); Mobile: OpenGL ES 2.0; Consoles: Xbox 360, PS3.

All image effects automatically disable themselves when they can not run on end-users graphics card.

Page last updated: 2012-01-09