CPT files are image files in the native format of Corel Photo-Paint. Photo-Paint is the image editor of the CorelDraw Graphics Suite and is not available separately. Similar to Adobe Photoshop, Photo-Paint offers many features for professional image editing and is used quite often in prepress.
CPT files are image files that can contain masks, layers, shapes and lenses in addition to the actual image information. Grayscale, CMYK and LAB color space are supported.
The CPT format is proprietary and as of version 7 can only be read or converted by Corel products. In addition, the format is not 100% backwards compatible and even newer versions of Photo-Paint (X-Series) can not read pictures from older versions 6 and below. Note that Corel PaintShop Pro can not handle CPT files.