Vulkan pixel formats

The pixel formats in Vulkan usually follow the scheme:

VK_FORMAT_{component-format|compression-scheme}_{numeric-format}

optionally followed by the suffix _PACKnn or _BLOCK.

The component-format part specifies the sizes and order of the components. Each component is immediately followed by its size in bits (e.g. R8). The numeric-format part describes the type of each component.

There are broadly three categories of Vulkan formats:

• Non-packed formats: VK_FORMAT_{component-format}_{numeric-format}

  The component-format specifies the order and sizes of the components in memory, with the leftmost component stored at the lowest address and the rightmost component at the highest address. When a component consists of multiple bytes, the order of the bytes depends on system endianness.

  Example: VK_FORMAT_R8G8B8A8_SRGB

  Always stored as R, G, B, A in memory (R at the lowest address, A at the highest)

  Example: VK_FORMAT_R16G16_UNORM

  Stored as R₀, R₁, G₀, G₁ in memory on little-endian systems (R₀ at lowest address, G₁ at highest)

  Stored as R₁, R₀, G₁, G₀ in memory on big-endian systems (R₁ at lowest address, G₀ at highest)

  (R₀, R₁ are the first and second bytes of the R component, respectively)

• Packed formats: VK_FORMAT_{component-format}_{numeric-format}_PACKnn

  The component-format specifies the order and sizes of the components in a nn-bit native type, with the leftmost component stored in the most significant bits, and the rightmost component in the least significant bits.

  The memory layout of packed formats depends on system endianness.

  Example: VK_FORMAT_R5G6B5_UNORM_PACK16

  Stored in memory in the same way a 16-bit native type would be stored on the system. R is in bits 11-15 of the native type, G in bits 5-10 and B in bits 0-4.

• Block/compressed formats

  We won’t describe these in detail in this guide.