DDS to HEIC Converter

Encoding: the DDS uses block compression (BC1 to BC7, also called DXT) or uncompressed RGBA; HEIC uses lossy HEVC (H.265) intra coding, on iPhones as a grid of 512×512 tiles, and the download is a HEIF file whose picture is JPEG-compressed rather than HEVC, because no HEVC encoder runs in a browser.

Bit depth: 8 bits per channel for common texture formats in the DDS; HEIC allows 8 or 10 bits per channel, and the HEIC written here has 8 bits per channel.

Colour: RGB(A); normal maps and packed masks store data rather than colour in the DDS; HEIC supports YCbCr, usually tagged Display P3 on iPhones, written here as 8-bit sRGB.

Transparency: the DDS stores it as alpha inside the compressed blocks (BC2, BC3, BC7) or a 1-bit cut-out (BC1); HEIC could hold it as an auxiliary image item, rarely used by cameras, but this writer flattens it, so transparent areas are filled with the colour you choose.

Other images: the DDS can hold mipmaps, cubemap faces or texture arrays; only the main image is converted.

Metadata: the DDS can carry a 128-byte header (plus a DX10 header) describing the pixel format, nothing about the picture; HEIC can carry EXIF, XMP and an ICC profile, stored as items, but nothing is copied across.

DDS is a GPU texture format used by DirectX games. It stores block-compressed textures (DXT/BC) and mipmaps that graphics cards decode directly.

A DDS file starts with 'DDS ' and a 124-byte header giving the size, mipmap count and pixel format: a FourCC such as DXT1 or DXT5, or 'DX10' followed by an extra header naming a DXGI format. The largest mipmap comes first.

DDS files usually come from DirectX games, game mods and texture tools such as NVIDIA Texture Tools and Intel's texture plugin.

HEIC is the default photo format on iPhones and many Android phones. It is about half the size of JPEG, but Windows, many websites and older software cannot open it without converting.

A HEIC is a HEIF file (ISO base media boxes with the brand 'heic'). iPhone photos store the picture as a grid of 512×512 HEVC tiles that the decoder stitches together, with the thumbnail, depth map and HDR gain map as further items.

HEIC is the better choice for storing photos on Apple devices, while DDS suits game textures and mods.

HEIC strengths: About half the size of JPEG; Stores depth maps, Live Photos and HDR. Drawbacks to weigh: Not supported by most websites and Windows apps; Patent-encumbered codec.