Masks are the main tools provided to the user of GMask. They are used for masking, that is, the scrambling of the contents of an image in such a way that the user is puzzled to reveal them.

List of masksEdit

Rotate RGBEdit

Main article: Rotate RGB

Rotate RGB shifts the red, green, and blue (RGB) color channels of the image.

Xor 0x80Edit

Main article: XOR 0x80

Xor 0x80 alters the colors of the image.


Main article: Flip

Flip up-down and Flip left-right flip the image.


Main article: Negative

Negative inverts the colors of the image.

Glass BlocksEdit

Main article: Glass Blocks

Vertical Glass Blocks and Horizontal Glass Blocks divide the region into columns and rows (respectively), then flipping each row horizontally or vertically.

Win MaskEdit

Main article: Win Mask

The Win Mask divides the region into thin single-pixel columns and shuffles them.

Meko MaskEdit

Main article: Meko Mask

The Meko Mask and Meko + Mask divide the region into 16x16 blocks and shuffle them.

FL MaskEdit

Main article: FL Mask

The FL Mask creates a characteristic spiral pattern of the region.

Q0 MaskEdit

Main article: Q0 Mask

The Q0 Mask is equivalent to simultaneous use of "Negative", "Vertical Glass Blocks", and "Horizontal Glass Blocks".

CP MaskEdit

Main article: CP Mask

The CP Mask uses a user-input password to create a mess that's only solvable if the same code is used to reverse it.


Rotate RGBXOR 0x80FlipNegativeGlass BlocksWin MaskMeko MaskFL MaskQ0 MaskCP Mask
GMaskFLMASKGIMP MaskLinux GMaskZMask