CDR is proprietary to CorelDRAW
CDR is the native file format of CorelDRAW. Its internal structure is closed, so the reliable way to create a CDR is to open or import your artwork in CorelDRAW and save it there.
Need a CDR from a RGB? Here's why that isn't a direct conversion — and the editable formats that get you there.
You can't convert a RGB to CDR — CDR is CorelDRAW's own format, and only CorelDRAW writes it.
CDR is the native file format of CorelDRAW. Its internal structure is closed, so the reliable way to create a CDR is to open or import your artwork in CorelDRAW and save it there.
Even after importing, a RGB is pixels — not the editable shapes, text and layers a CDR is designed to hold. So a direct RGB → CDR conversion wouldn't give you a truly editable document anyway.
RGB is Silicon Graphics' image format from SGI Unix workstations, storing uncompressed or RLE-compressed color used in early 3D and film work.
How to open RGB opens in GIMP, ImageMagick and SGI-era tools; convert to PNG/TIFF for modern editors.
Full RGB format guideCDR is CorelDRAW’s native vector format for logos, layouts and print artwork — proprietary to Corel software.
How to open CDR opens in CorelDRAW; convert images to CDR to join a Corel workflow.
Full CDR format guide