FidelityFX Blur

FidelityFX Blur demonstrates a single pass Gaussian blur effect which is functionally the same as a standard two pass separable Gaussian blur (but more performant).

For details on the techniques that underpin the FidelityFX Blur effect you can refer to the respective technique documentation .

FidelityFX Blur


Windows DirectX(R)12 Vulkan(R)

UI elements

The sample contains UI elements to switch between different Gaussian kernel weights, different kernel sizes, and floating point precision. Also the UI provides a comparison mode to compare the FidelityFX Blur technique to standard blur techniques. The table below summarises the UI elements and what they control within the sample.

Element name




FidelityFX Blur, Single Pass Filter, Multi-pass Separable Filter, Multi-pass Separable Filter Transpose

Switches the currently used algorithm.

Gaussian Kernel Sigma

1.6, 2.8, 4.0

Switches the sigma used for generating the Gaussian kernel.

Kernel Size

3x3, 5x5, ..., 21x21

Switches the size of the blur kernel.

Floating Point Math

Use FP32, Use FP16

Switches between FP32 and FP16 implementations of the technique.

Display the difference


Enables/Disables the comparison mode.

Comparison mode settings

Compare Algorithm, Compare Gaussian Sigma, Compare Kernel Size, Compare FP Math

Same options as above, but for the comparison mode filter.

Diff Factor


Scale to apply to the comparison difference for display.

Comparison Mode

The comparison mode, which is enabled by selecting the Display the difference between two algorithms checkbox, displays the difference between the two selected blur algorithms.

The image generated by the algorithm selected in the Compare Algorithm dropdown and its corresponding kernel sigma, size, and math settings, are subtracted from the image generated by the algorithm, and corresponding settings, selected in the Algorithm dropdown. In order to better visualize very tiny differences, the Diff Factor slider specifies a value that the difference between the two images is multiplied by before it is displayed on screen.

Sample Controls and Configurations

For sample controls, configuration and Cauldron UI element details, please see Running the samples

See also