The CPT file extension is associated with Corel PHOTO-PAINT, a raster graphics editor developed by Corel. CPT files use Corel PHOTO-PAINT's own bitmap format to store edited digital photos. In other words, they are graphic files with distinct layers, alpha channels and transparency, all of which allow for future image editing. CPT is very similar to the TIFF format in terms of image quality and size, but the latter tends to be more popular and easier to handle using regular image viewers.
JPEG JPG PNG GIF TIFF TIF BMP ICO EMF WMF AI PDF EPS PS EPI WEBP WEBPLL JP2 PCX TGA DWG DWF DXF DGN WMZ CGM DRW GBR PCT MIF PLT PCL SVG WPG CIN DCX DIS HRU MTV PRC RAD PIC RLA QRT SGI XBM XPM SWF CAL PSD JXR BPG APNG DDS SVGZ CG4 FLIF