ICO is a image format: it bundles multiple raster images at different resolutions (16x16 through 256x256) into a single file for use as application icons. PSD is a image format that preserves non-destructive editing layers, masks, adjustment layers, and smart objects in a proprietary Adobe format. This conversion changes the file's encoding, compression method, and supported feature set. Colour profiles and orientation metadata are preserved in the output. Converting between these two formats is common when the source application does not support PSD natively or when the target platform only accepts PSD. 1converter processes this conversion server-side using open-source tools. Files are transferred over HTTPS, converted on secure cloud servers, and automatically deleted after 24 hours.