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include "../import.h"
# IPCMAP.X -- Procedures for colormap application or lookup.
# IP_GRAY_CMAP - Apply the colormap to an array of pixels and convert the
# pixels to grayscale using the NTSC formula.
procedure ip_gray_cmap (data, len, cmap)
char data[ARB] #i pixel values
int len #i how many of 'em
pointer cmap #i colormap pointer
int i
short val, ip_gcmap_val()
begin
do i = 1, len {
val = data[i] + 1
data[i] = ip_gcmap_val (val, cmap)
}
end
# IP_GCMAP_VAL - Apply the colormap to a single pixel and convert the
# result to grayscale using the NTSC formula.
short procedure ip_gcmap_val (pix, cmap)
char pix #i pixel value
pointer cmap #i colormap pointer
short val
begin
val = (R_COEFF * CMAP(cmap,IP_RED,pix) +
G_COEFF * CMAP(cmap,IP_GREEN,pix) +
B_COEFF * CMAP(cmap,IP_BLUE,pix))
return (val)
end
# IP_RGB_VAL - Given a grayscale value figure out what the requested color
# component is from the colormap.
short procedure ip_rgb_val (pix, cmap, color)
char pix #i pixel value
pointer cmap #i colormap pointer
int color #i requested color
short i, val
begin
# Need to optimize this later... For now just compute the colormap
# grayscale values until we find a match and use the index.
i = 0
val = -1
while (val != pix && i <= 256) {
i = i + 1
val = (R_COEFF * CMAP(cmap,IP_RED,i) +
G_COEFF * CMAP(cmap,IP_GREEN,i) +
B_COEFF * CMAP(cmap,IP_BLUE,i))
}
switch (color) {
case IP_RED:
val = CMAP(cmap,IP_RED,i-1)
case IP_GREEN:
val = CMAP(cmap,IP_GREEN,i-1)
case IP_BLUE:
val = CMAP(cmap,IP_BLUE,i-1)
}
return (val)
end
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