260f542b__to_Good_Practice__RasterImg_2__Recommendations
[Format] .cpt [Properties/Technologies] Corel Photo-Paint image, a proprietary format owned by Corel. Primarily used for creating or editing images. [Description] CPT is the native format of Corel's Photo-Paint software and, as the main competitor to Adobe Photoshop, provides a similarly wide range of functionality. [Recommendations] 
As with the PSD format, CPT is ideally suited to the creation and editing of images and, while copies may be kept in this format for possible future editing, the format is highly specific to Corel software and copies of images should be stored in uncompressed formats such as TIFF.
Guides to Good Practice: RasterImg_2
Recommendations