Someone with a Nu theory that's as simple as Pi to understand.

OMEGAwd! . . . Hey guys . .. I am being a tad serious on this! but yeah . . .Friday nite had to many Guinesses . .gotta a bit PSyed . ..

But yes, I'd really would like to know from whence they came . . . it would help me to remeber the reasons for their usage . .yeah?

Grazie

Don't think there's any particular reason why anyone was chosen, same as our use of English symbols such a XYZ.
Probably Greek was used to avoid confusion, I mean saying you need to adjust the Gee, well that wouldn't work cause we use that for something already. Also not too many english speaking people know how to spell "G" whereas gamma they are more likely to recognise.

Just guess of course.

Perhaps in the old days when painting started they used those terms, HO !!Michael, leave an Alpha Channel on the celing for my background..

It is used in Physic's so why not...

According to John Caponigro (Photoshop author/trainer), it's because the art of cutting images manually blocked the primary, or alpha, view and allowed only the secondary information to pass through. That doesn't make a whole lotta sense in the context of today...but it could be true.
Gamma is a whole different tiger. you got my curiosity up too, so started searching some of my books, can't find anything in there at all. Online all I could find was:
Gamma \Gam"ma\, n.
The third letter ([Gamma], [gamma] = Eng. G) of the Greek
alphabet.

<language> 1. A language for matrices and generation of
mathematical programming reports.

2. A high-level parallel language.

[Research Directions in High-Level Parallel Languages,
LeMetayer ed, Springer 1992].

(1994-11-29)

It's still all Greek to me. (The etymology

The Alpha channel was invented by Alvy Smith and Ed Catmull.
Alvy got an academy award and explained the process and the name:
"we called it that because of the classic linear interpolation formula (alpha)A + (1-(alpha))B that uses the Greek letter (alpha) to control the amount of interpolation between"

You can read about it in http://www.cs.princeton.edu/courses/archive/spring04/cos426/papers/smith95c.pdf

Udi

Very interesting and informative reading, thanks for sharing! Now the truth is known. I wonder where Caponigro came up with his history. Sounded good to me.

Can someone explain to me who uses Gamma? I'm not sure I've ever heard it in the computer graphics world.

Plenty of times in physics and psycology, but not computer graphics.

JBJones


P.S. Boy do I feel stupid. About the time I hit the "post message" button the phrase popped into my mind....
"need to make sure the gamma is set correctly on your monitor."

Must have been a glitch in my brain.

Not only do I feel a little bit stupid from what happend in my last post. But to make matters worse I have a little bit of knowledge that might help determine why it's called gamma. It's not conslusive, but might allow an educated guess. I started to expound on this personally, but when checking my facts I found this nicely worded definition over at....
http://www.plexoft.com/SBF/C12.html

Definition
Cathode Ray Tube. Despite the somewhat general name, the term refers specifically to video-screen tubes. The name reflects history: Edison discovered that a hot filament in an evacuated bulb could cause a current to flow (the ``Edison effect'' which we recognize as thermionic emission of electrons). Since the Edison effect current was a flow of electrons, it could only flow from the cathode to the anode, and not in reverse -- thus ``cathode rays'' and the first vacuum tube diode. Application of a magnetic field demonstrated that various beams that could be produced were positively charged (alpha rays), negatively charged (beta rays), or neutral (gamma rays, X-rays). Beta rays could be detected by the phosphorescence of certain coatings on the inside of a tube, and a beta beam could be focussed and directed electrostatically, so: oscilloscopes! And eventually, alas, oscilloscopes remotely controlled by AM radio signals, raster-scanned to produce images, and, alas, TV.

So back to my own thoughts, when you are adjusting the gamma for your monitor you are basicly setting the middle gray point. On an 8 bit scale that would be the level of gray #128 which is half way between black #0 and white #255. Since neutraly charged rays are called gama rays perhaps the designers used the same term to refer to the neutral grey point.

JBJones

It's normaly switched around with "brightness." I know some computer games say "gamma" and some say "brightness". I know in some games to adjust the brightness manualy you type a value in for gamma. Go figure. :)

Dont feel bad. At my old job I was writing instructions on how to do stuff in Premiere 6. In the trimmer they list the delta (a little triangle) for the difference between the in/out points. My boss, who worked at a nuke plant before going into businness for himself, didn't know what delta meant. :)

I have no problem with not kowing things. It doesn't bother me at all to ask questions. When I feel bad is when I know something, but don't know that I know it.

JBJones

JbJones . .firstly I really think you are definatley onto something . .honest . .SECONDLY are you also aware you have an uncany "namesake" to the discoverer and developer of the Magnetron and the start of the RADAR revolution here in the UK? AND you know about oscilloscopes - THE main viewing device for the "spikes" for the returning wave for the operatoprs to "gauge" the hieght and distance . . .and therefore the speed of incoming "aircraft" . .? Did you know that? I'm almost certain Jones was the name of the guy . .?

. . .hmmmm .. .

Grazie