From Wikipedia: http://en.wikipedia.org/wiki/Greyscale
'Converting color to grayscale
To convert any color to its most approximate level of gray, first one
must obtain the values of its red, green and blue (RGB) primaries.
Then, add 30% of the red value, 59% of the green value, and 11% of
the blue value, together. Regardless of the scale employed (0.0 to
1.0, 0 to 255, 0% to 100%, etc.), the resultant number is the desired
gray value, such that a new RGB color would have red, green, and blue
values equal to the new number. These percentages are chosen due to
the different relative sensitivity of the normal human eye to each of
the primary colors (less sensitive to green, more to blue).'
Cheers,
Luis.
On 29 Nov 2007, at 09:54, Luis wrote:
Hiya,
Some time ago we used to add the RGB values together and then
divide by 3. This was waaaay back, and the results were ok then.
I spotted this on the net:
R*.3+G*.59+B*.11 to get the grey value, haven't tried it.
Cheers,
Luis.
On 29 Nov 2007, at 00:39, Ken Ray wrote:
On Wed, 28 Nov 2007 20:50:11 -0200, Andre Garzia wrote:
Ken,
Have you tried snapshoting the card, then somewhere off screen
you put
a gray image on top of the snapshot with some blend and take another
shot. Depending on ink combinations you might have a nice result.
Good idea - I'll compare that speed-wise with other suggestions
people
have made.
Another way, which I don't know how fast it is, is to read each
pixel
in the snapshot and convert it using some proportional gray value.
Yeah, that was Chipp's suggestion - which I might use too - took
about
500ms on a 400x400 image on my MacBookPro.
Ken Ray
Sons of Thunder Software, Inc.
Email: [EMAIL PROTECTED]
Web Site: http://www.sonsothunder.com/
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