vjurgens@ncsa.uiuc.edu (Vincent Jurgens) (06/05/91)
We're looking to make some image files, 1280x1024, to test fiber xmission, and frame buffer output. Do you know of anyone, academic or commercial, who's already done this, or has a program to generate them? Or anyone who has comprehensive hi-res colorimetry/performance/technical experience? We wanted image files so there would be device independance. We could do it with a paint or draw program, but it'll take forever. And our local vis software people are swamped now. My engineer's note follows. Thanks, Vincent Jurgens, NCSA vjurgens@ncsa.uiuc.edu ---- From: Mark Lumos WRT: Video Test Signals I am presently developing the specifications for the signals we will use to test the hi-res fiber optic transmitters and receivers. I think I have most of what we need described, but I would like input from the rest of you. I propose 5 test signals - 1 each for alignment/gain set, bandwidth measurement, crosstalk detection, low frequency linearity, and high frequency linearity. Furthermore, I am calling for suggestions for a 6th test, which I am calling subjective for lack of a better term. Does anyone know of any particular image or images that they feel would make a good subjective, gut-level-reaction type of test of image transmission quality? I could specify more technical testing, but I believe I have the areas covered that are important. I also know that some times subjective testing will illuminate problems in a transmission system that standard testing methods can miss. That is why I am asking you to suggest an image or images. Test signal 1 is an adaptation of the standard multiburst signal used in television. It employs 2 long-time-constant areas of black and white for calibration purposes, and then alternating patterns of black and white, at the maximum rate the machine can generate, and at one half and one fourth the maximum rate. This should give us a rough idea of any high-frequency amplitude distortion in the system under test. I expect less than 5% gain distortion at the highest frequency in use. Test signal 2 will be used for crosstalk detection. It consists of an all black field in the red and blue channels, with a high-frequency transition at the center of the green field. I do not expect there to be any significant crosstalk in any of the systems tested, but it never hurts to check. Test signal 3 will be used to test low-frequency linearity. It consists simply of a series of amplitude steps of equal value. I expect low-frequency linearity distortion to be less than 3%. Test signal 4 will be used to test for high-frequency gain distortion at varying luminance levels. I expect any differential gain to be less than 5%. Test signal 5 is color bars, and will be used for general gain adjustment and alignment. Please send me your questions, comments, and suggestions. Mark Lumos, NCSA