In this thesis, the implementation and characterization of a digital photo printer based on silicon display are presented. A silicon display is used as an image source and images are printed on Fujifilm instax mini instant film. The printout achieves a resolution of more than 400 pixels per inch and 32 halftones....[ Read more ]

In this thesis, the implementation and characterization of a digital photo printer based on silicon display are presented. A silicon display is used as an image source and images are printed on Fujifilm instax mini instant film. The printout achieves a resolution of more than 400 pixels per inch and 32 halftones.

The silicon display has spatial resolution of 688 x 480 and 16-bit color per pixel. For photo printer application, a special circuit, namely XGA2SDTV process, is designed to put an image of 1024 x 768 spatial resolution on the silicon display. Time sequential color method is used to produce color printouts. The XGA2SDTV process is implemented on Xilinx Spartan2 Field Programmable Gate Array (FPGA) platform. It costs about 34000 equivalent gate counts and can run up to 85.75MHz.

Two circuit boards are designed for the photo printer. The first one uses Xilinx FPGA as core. The printer controller, SDRAM controller and silicon display controller is implemented in the FPGA. The board is controlled through software running on PC. The second board uses TI DSP platform. The board directly reads image data from memory cards and decodes the compressed image data in JPEG file. The board can support stand-alone operation without connecting to PC.

A procedure for simple characterization of the photo printer is designed, and output qualities are measured for different illumination time values. The red, green and blue illumination time value are optimized based on objectives, namely, uniformity of lightness, maximum output range of lightness, linear gradient in lightness, maximum output range of chroma and linear gradient in chroma. Using the optimum illumination time values, the color gamut in CIE chromaticity x, y values of (0.56, 0.35) for red, (0.30, 0.55) for green and (0.19, 0.11) for blue is obtained.