Question about alpha mask

I noticed that every time when i render separate alpha pass for object in Blender its not completely black and white. I think its wrong. Should i use color ramp to make it proper BW or should i stick to what Blender does because this mask is actually correct?

What color is it if it’s not black and white?

Here you go mate. Without color ramp and with color ramp compare

So first one a bit more greyish. Black is also a bit off - but black you cannot see by eye but white is obviously has change

Something funky going on there. How do you render the alpha pass and what output from render layer are you writing to image? Any material override going on there maybe? An alpha output from renderlayer can not be colored, I guess you take that colored image from some other pipe there…

Maybe you right. Look at that…If there something wrong tell me please

Doesn’t look wrong. Any chance of uploading the sample blend file or the resulting colored image file?