Hello,

I wonder if there is any object can detect the number or the percentage of black
（RGB= 0 0 0） pixels at current frame

cos I am on a project which interactivity depends on graphic detection

10000000000000000 thanks

Tone～

i don't believe, that there is a special object for this, but you could try to filter the image at first, maybe with pix_mask. or try to chroma key the rest of the pic away.
after there is only black left, use pix_mean_color to calculate the percentage.
not sure if it'll work out, but might be worth a try. (check the help files to these objects as well)

[pix_blob]
might be what you are after.
http://en.flossmanuals.net/PureData/GEMVideoTracking

i can't remember, whether it actually measured the "weight" of black in the gemwin or only the weight in an image or video. in the latter case, you could always texture all gemwin contents on a rectangle and then measure that.