I've been saying for a long time that Avalon needs blend modes (or Merge-Modes for Corel users like me). I need to back my request with solid evidence. So, here it is.
These are examples of the 2 blend modes used the most (at least by me and a few hundred game developers) - Add (lightens), and Subtract (darkens).
Example 1
Image 1a - a vector based sphere and the Pwop logo with Add (aka Additive) mode applied.
Image 2a - the same graphic without blend modes.
Example 2 & 3
2a/3a: A lightning bolt and a sparkle/lensflare/shine thingy (32-bit transparent raster image) without blend mode on a simple white background.
2b/3b: Same objects on a multicolored/textured background - better but still not that cool.
2c/3c: Additive mode applied to both object - the color values of the underlying pixels is added to the overlaying pixels and the result is a more natural looking glow.
Example 4
Colors often clash - making some parts totally ugly. One such combination is a blurred/transparent-gradient black over a yellow backdrop. (see 4a)
Now, we add a Subtractive blend more to the shadow layer - and voila - subtracts it's own value from the underlying pixel giving you a more natural tone.
Example 5
Okay, so we've seen the visual part of blend modes - now let's see the functional part of it.
We have a hypothetical software called X-Rayvalon. This app can be used by doctors to teach students or show vital info to their patients. A doctor wants to highlight a whole region where a certain ailment is shown in an x-ray. He or she draws a square, as if selecting files in Explorer, on the x-ray. (3 such rectangles shown in 5a)
Under the hood a rectangle object (5b) is created with a fill of R:51/G:51/B:51 and a solid border of R:102/G:102/B:102. The underlying image is not hindered by this rectangular overlay because unlike normal transparency the colors of the image (at least in terms of pixel intensity) is preserved.
In this image below, you can see colored versions of the same - say a visual discussion by a group of doctors - each assigned a color.
It doesn't take much imagination to see the possibilities in a million different applications.
Windows does support blend modes in GDI/GDI+ - that blue selection box in XP/Explorer is a subtract or some other blend mode.
With Avalon, the possibilties are greatly increasing. Blend modes would be a VERY valuable asset to this.
Related post on Channel9 >>
Follow up blog entry >>