Sourced images for compositing
Yo u h a ve s o u rc e d t h e i m a g e s y o u t h i n k w o u l d w o r k to g e t h e r, a n d y o u n e e d
to check if the glass will sit realistically on the table, if the angles will line up
and if the perspective will be convincing. However, you are so squeezed for
time that even a rough trace of the glass would take too long. Luckily for
you, the glass of milk has a black background.
Removing Black or White
Photoshop offers ready-made blending modes for removing black and
white from one layer placed on top of another. The Multiply blending mode
will render white pixels transparent, while the Screen mode does the same
with black pixels. Both blending modes will also affect how other tones in
your layer interact with the layer below, so unless this effect is something
you are going for, this technique is usually best used to preview images
which are on solid black or white backgrounds. This is massively time