lauren (02/01/83)
Greetings. This news item may be a repeat for some sites due to a netnews control message problem. Sorry for any inconvenience. Following is the image format information memo for VVS... ----- ------------------- VORTEX VIDEO SYSTEM ------------------- Image Format ------------------- Last updated: 1/24/83 This file is: "vortex!/pix/format". Currently, all images are stored in a straightforward, non-compressed format. Images are digitized as 256 by 256 pixels. Pixels are 4 bits wide and represent a grayscale value ranging from 0 to F (hex). For each pixel, 0 represents darkest BLACK, and F represents brightest WHITE. The individual bits are weighted in the image for a standard grayscale: the relative weights are 1 for the most significant bit, 1/2 for the next bit, 1/4 for the next, and 1/8 for the least significant bit in the pixel. Each VVS image file is 32768 bytes long. The byte stream represents the scanned video image starting at the upper-lefthand corner of the image, progressing to the right to the end of the first scan line, then continuing at the lefthand edge of the second scan line, and so on. Image layout (bytes): line 1 0 1 2 ... 128 line 2 129 130 131 ... 256 . . . line 256 16256 16257 16258 ... 16384 Each byte contains 2 pixels, with the "first" pixel in the high order nibble of each byte: 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 |-----------|-----------|-----------|-----------| | pixel 1 | pixel 2 | pixel 3 | pixel 4 | ... |-----------|-----------|-----------|-----------| byte 1 | byte 2 Unless otherwise noted, all current VVS images are digitized to broadcast video standards: 4:3 aspect ratio with 240 active display lines. The last 2048 bytes of each image (lines 241 through 256) are set to 0 to provide full image blanking on standard 256 X 256 graphics displays. Most current VVS images have a typical actual pixel value range of 0 through A or B (hex).