Francesco Scarfato <[EMAIL PROTECTED]> wrote:
> hello everybody, i've a trouble with getPixel.
> if fill the stage with shapes that have the follow color
>
> rgb(255, 000, 000) --> red
> rgb(000, 255, 000) --> green
> rgb(000, 000, 255) --> blu
>
> than i copy some shapes on the stage with fill (o simple drag on the stage
> cast member that have these parameters).
> when i try to read the color of pixel on the stage with getPixel, as in
> follow
>
> on mouseUp
> put (the stage).image.getPixel(the mouseLoc)
> end
>
> i've these result
>
> instead of rgb(255, 000, 000) getPixel return rgb(248, 000, 000)
> " rgb(000, 255, 000) " " rgb(000, 248, 000)
> " rgb(000, 000, 255) " " rgb(000, 000, 248)
>
> and so on for every pure colors likes rgb(255, 255, 000) even rgb (255, 255,
> 255) --> white is return as rgb(248, 248, 248)
>
> someone have a solution?
Hi Francesco,
My guess is that your monitor is set to 16-bit (High Color or Thousands of
Colors). In 16-bit mode, each color is coded as 5 bits of red data, 5 bits
of green data and 5 bits of blue data, plus 1 unused bit:
arrrrrgggggbbbbb
This means that you can have values between 0 and 31 (32 values in all) for
each color channel.
In 24- and 32-bit depth, can have values between 0 and 255 (256 values in
all) for each color channel.
How big is the gap between each channel value in 16-bit color? Not 256 / 32
but 255. / 31, or 8.2258... (Think about it).
As you may already know, computer processors work fast when performing
calculations in powers of 2 (2, 4, 8, 16, 32, ... 256, and so on). On the
other hand, floating point calculations, such as multiplying by 8.2258...
are much slower. As a result, when Director expresses a 16-bit color in its
rgb() format (which is designed for 32-bits), it does so by multiplying the
16-bit values by 8:
rgb16{0, 16, 31} => rgb( 0, 128, 248 )
In other words, your results are consistent with performance optimizatios
for 16-bit mode.
Cheers,
James
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