PNG to ARW Converter

Encoding: the PNG uses lossless DEFLATE with a prediction filter chosen per row; ARW uses Sony's lossy compressed raw, uncompressed (since the A7R II) or lossless compressed (since the A1), and the download is a Linear DNG: demosaiced 8-bit RGB with the colour matrices raw editors need.

Bit depth: 1, 2, 4, 8 or 16 bits per channel in the PNG; ARW allows 12 or 14 bits per channel, and the DNG written here has 8 bits per channel, linearised. 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; ARW supports camera RGB from a Bayer mosaic, written here as 8-bit sRGB.

Transparency: the PNG stores it as a full alpha channel, so edges and shadows can fade smoothly; the DNG has none, so transparent areas are filled with the colour you choose.

Metadata: the PNG can carry text chunks, an ICC profile, physical resolution and EXIF in an eXIf chunk; ARW can carry EXIF, Sony maker notes, a thumbnail and a full-size JPEG, 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.

ARW is the raw format of Sony Alpha, RX and Cyber-shot cameras. It stores the sensor data (compressed, uncompressed or lossless compressed, depending on the model) with a full-size JPEG preview.

ARW is TIFF-based: the first directory carries EXIF and Sony's JPEG preview and the sensor data sits in a sub-directory. In Sony's classic compressed raw each block of 16 same-colour pixels keeps an 11-bit maximum and minimum plus 7-bit steps for the rest, which can leave artefacts beside high-contrast edges.

ARW files come from Sony Alpha mirrorless and SLT cameras, RX compacts and some Cyber-shot models.

Forms and workflows that ask for ARW usually feed a raw editor, and each of those opens DNG as well, so the DNG can take the ARW's place. Keep the PNG if you only need to view or share the picture.

What ARW offers when it comes straight from the camera: A full-size JPEG preview from the camera; Lossless compressed raw on recent bodies; Wide support across Sony's long Alpha line. Its drawbacks: Sony's classic compressed mode is lossy; Uncompressed files of 60 MB and more on high-resolution bodies; Creative Looks are ignored by most third-party raw editors.