I downloaded some PSD files, which is a file format by Photoshop. I tried to open it with GIMP, can be known as most popular open source image editor. However, opening the file showed some error message,

Error loading PSD file: Unsupported color mode: CMYK

Then I tried to install the “gimp-plugin-separate”, but it does not work. According to this post, the author also mentioned that “gimp-plugin-separate” does not work. But, the author mentioned some solutions. One of the solution is using “imagemagick” to convert the file into several PNG files.