[Cin] Some tests on blending

[Andrea paz]

With:

printf ("%g\n", R(0));

gives me a very long series of “1's”; perhaps a result for each pixel
of the 1920x1080 frame?

With:

if (PIX_X == 0 && PIX_Y == 0) printf ("%g\n", R(0));

It gives me a simple “1” for all plugins, with very few exceptions
when the frame is replaced by other colors for which the different
value is shown (always under “1”).
For example, “Color Swatch” replaces the solid red with its own
palette and then the result depends on the new color of the pixel
(0,0). Another example is “Lens” which causes the red frame to shrink
to a central part leaving the rest (including the pixel (0,0)) black.
In fact the result is “0” and not “1”). However, by changing the Blend
Program function and setting X=960 and Y=540 (i.e., the center pixel,
where Lens still produces solid red) the result is still “1”.
Other exceptions are HistEQ which turns the whole frame black and thus
the result is “0,” Histogram Bezier which gives 0.999996 (which is “1”
anyway) and Posterize which gives 0.99678.

I can't interpret the results: I always get 1, even for Choma Key
(Avid) and for Blender Algebra itself. I have tried all the internal
plugins of CinGG, even those of only geometric transformations (Scale;
Transform; Lens; DownSample, etc) and the result is always “1”.
Maybe something limits (clips) the signal regardless of the plugin
used? Perhaps the print_hdr.bp function is not suitable for checking
the actual pixel value?

I think the issue is too complicated so it's better to give up.
However, I better understood Blend Algebra and Blend Program and their
tremendous possibilities.