PNG to EXR Converter

Encoding: the PNG uses lossless DEFLATE with a prediction filter chosen per row; EXR uses none, RLE, ZIP, PIZ, PXR24, B44 or DWA, chosen per file, and the download is a ZIP-compressed OpenEXR with 16-bit half-float channels, the 8-bit sRGB values converted to linear light.

Bit depth: 1, 2, 4, 8 or 16 bits per channel in the PNG; EXR allows 16-bit half or 32-bit floating point per channel, and the EXR written here has 16-bit half float per channel. 16-bit PNGs from photo and scientific software are reduced to 8 bits per channel.

Colour: RGB, greyscale, or an indexed palette of up to 256 colours in the PNG; EXR supports scene-linear RGB, often ACEScg or linear Rec.709, written here as linear-light RGB.

Transparency: the PNG stores it as a full alpha channel, so edges and shadows can fade smoothly; the EXR keeps it as an A channel stored like any other channel.

Metadata: the PNG can carry text chunks, an ICC profile, physical resolution and EXIF in an eXIf chunk; EXR can carry named header attributes such as chromaticities, timecode and camera data, but nothing is copied across.

PNG stores pixels losslessly with full alpha transparency. It is ideal for screenshots, logos, UI and anything with sharp edges, but photos saved as PNG are several times larger than JPEG.

A PNG opens with an 8-byte signature and is a chain of chunks, each with its own CRC: IHDR (size, depth, colour type), optional PLTE and tRNS for palettes, one or more IDAT chunks with the compressed rows, and IEND.

PNG files usually come from screenshots, design exports, logos and web graphics.

OpenEXR is the high dynamic range format of film visual effects. It stores half or full floating-point channels in linear light, plus any extra render passes, and is the working format of compositing pipelines.

An EXR starts with the magic number 76 2F 31 01 and a version field, then a header of named, typed attributes (channels, compression, dataWindow, displayWindow) and a table of offsets to scanline or tile blocks.

EXR is the better choice for visual effects, compositing and 3D render output, while PNG suits screenshots, logos, graphics and anything that needs transparency.

EXR strengths: True high dynamic range in linear light; Any number of channels and render passes; Lossless compression options. Drawbacks to weigh: Needs tone mapping to look right on a normal screen; Very large files; No browser or phone support.