See
http://www.teamphotoshop.com/photoshop/tutorials/techniques/ blendmode_2/blen dmodes_2.php
5. Multiply
Okay, this aptly named blend mode multiplies the base color by the blend color to give us the result color. It always results in darker hues. Let’s see why.
Look again at the images in the step above. I placed a color sampler down and took readings of each of the three colors used in the Multiply blend mode. You can see the numerical values from my Info Palette. The calculations for each of the RGB channels will be performed the same, so let’s just look at one, the Red Channel. In the Base Image, that’s a pretty light version of red, so you shouldn’t be surprised to see a high numerical value. It is 250. (Remember, 255 is white.) This is going to be multiplied by the red channel in our blend image, which you see has a value of 46. But those of you who think the answer should be 11,500 are failing to realize that our Blend Color (46) is going to be translated to its percentage value, which is 0.18 (46 is 18% of 255.) So the Result Color has a red channel value of 45, since 250 x 0.18 = 45. So you see, unless you’re blending a layer of complete white, the resulting colors can’t help but have a lower value (closer to Black) than the base colors, since you’re always multiplying by something less than 100%.
(If you want to understand the math better, try working out the blue channel and see how we got a result color value of 83.)
You can see my Multiply-ed result image at middle left, full of dark indigo and violet. At bottom left, I’ve lowered the opacity on my blend image to 50% so you can see another possible outcome.
wrote in message
When painting with the brush tool and the multiply option set in the paint
options, what is it doing?