&nbrs;Beyond Resolution


[ DCT encryption ] 
The legibility of an encrypted message does not just depend on the complexity of the encryption algorithm, but also on the placement of the data of the message. Here they are closely connected to resolutions: resolutions determine what is read and what is unseen or illegible.

DCT ENCRYPTION (2015) uses the aesthetics of JPEG macroblocks to mask its secret messages on the surface of the image, mimicking error. The encrypted message, hidden on the surface is only legible by the ones in the know; anyone else will ignore it like dust on celluloid.

While the JPEG compession consists of 6 steps, the basis of the compression is DCT, or Discrete Cosine Transform. During the final, 6th step of the JPEG compression, entropy coding, a special form of lossless data compression, takes place. Entropy coding involves the arranging the image components in a "zigzag" order, using run-length encoding (RLE) to group similar frequencies together.
How Not to be Read, a recipe using DCT:

  • Choose a lofi JPEG base image on which macroblocking artifacts are slightly apparent. This JPEG will serve as the image on which your will write your secret message.
  • If necessary, you can scale the image up via nearest neighbour interpolation, to preserve hard macroblock edges of the base image.
  • Download and install the DCT font
  • Position your secret message on top of the JPEG. Make sure the font has the same size as the macroblock artifacts in the image
  • Flatten the layers (image and font) back to a JPEG. This will make the text no longer selectable and readable as copy and paste data.

︎ for the #3D Additivist Cookbook.
︎ DCT won the Crypto Desgin Challenge Award in 2015.

A Discrete Cosine Transform simplified to make a monochrome .ttf font and iRD logo. In the logo RLE 010 000 - 101 1111 signifies the key to the DCT encryption: 010 000 - 101 1111 are the binary values of the 64 most used ASCII glyphs, which are then mapped onto the DCT in a zig zag order (following RLE).