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tvread([ ix, iy, nx, ny] [, window]
[, /greyscale])
tvread,[ ix, iy, nx, ny] , window [,
/greyscale])
[x11] Returns part of window window,
starting at ix, iy and of dimensions
nx, ny. The window part defaults to the whole
window, window to the last selected window
(!window). By default, the raw pixel values are returned,
without using color table information. If the result is displayed using
tvraw, then the original image appears - if the color table has
not been changed in the meantime. If keyword /greyscale is
specified, then the read pixel values are translated into (grey)
intensity values between 0 and 255 which are then returned.
If you read part of a window, then that part must be wholly within the
confines of the screen at the time it is read. There is no such
limitation on reading from a pixmap (with negative window).
Alias: xtvread