I compressed a color image, but my J2C only shows black and white when I try to view it on a PC.
The J2C header has no information about the color space so a computer cannot render all components together. You can only view the components separately. In order to view the codestream in full color, you have to create codestreams in the JP2 format which contains the color space information. With this, a software decoder on a PC can render all components together.
To use JP2, the encode parameter COD_STYLE bits 0:2 should be set to 010