PSD to BMP Converter

Encoding: the PSD uses raw or RLE (PackBits) channel data, ZIP in some 16 and 32-bit files; BMP uses usually none; RLE for some 4 and 8-bit files, and the download is an uncompressed 24-bit BMP, or 32-bit with alpha when the image has transparency.

Bit depth: 8, 16 or 32 bits per channel in the PSD; BMP allows 1, 4, 8, 16, 24 or 32 bits per pixel, and the BMP written here has 24 or 32 bits per pixel. 16 and 32-bit documents are reduced to 8 bits per channel.

Colour: RGB, CMYK, Lab, greyscale, indexed or multichannel in the PSD; BMP supports RGB or an indexed palette, written here as 8-bit sRGB.

Transparency: the PSD stores it as transparent layers plus extra alpha channels; the BMP keeps it as an optional fourth byte in 32-bit files, which many programs ignore.

Other images: the PSD can hold layers, masks, adjustment layers and smart objects; only the main image is converted.

Metadata: the PSD can carry XMP, EXIF, IPTC and ICC in image resource blocks; BMP can carry nothing beyond the header's resolution fields (and a colour profile in rare V5 headers), but nothing is copied across.

PSD is Adobe Photoshop's layered working format. It keeps layers, masks and effects, but almost nothing outside Photoshop can display it, so finished designs are exported to PNG or JPG.

A PSD has five sections: a header ('8BPS', channel count, size, depth, colour mode), colour mode data, image resources (thumbnail, ICC, XMP, resolution), layer and mask information, and finally the merged composite image that the Maximize Compatibility option saves.

PSD files usually come from Photoshop and apps that save Photoshop documents, such as Affinity Photo, GIMP, Photopea and Krita.

BMP stores raw, uncompressed pixels. Files are huge but trivially simple, which is why some legacy Windows software, embedded displays and printers still ask for it.

A BMP is a 14-byte file header ('BM' and the offset to the pixels), a DIB header (40 bytes, or 108 and 124 bytes in the V4 and V5 versions that add colour masks and alpha), an optional palette, then pixel rows padded to 4 bytes and normally stored bottom-up.

BMP is the better choice for legacy software and embedded systems that require it, while PSD suits editing in Photoshop.

BMP strengths: No compression artifacts; Read by very old and very simple software. Drawbacks to weigh: Enormous files; Poor support for transparency; No metadata.