Harvey_Taylor@mindlink.UUCP (Harvey Taylor) (02/21/91)
I am putting together a viewer for some raw b&w data & I have a
couple of questions.
It seems the maximum greyscale range I can get is 16. Why? It seems
to me I should be able to get 32 using EHB mode. Yes? No?
What are the pros & cons of displaying data in a superbitmap window
versus in a CustomBitMap attached to the screen?
In the A2024 docs [in the autodocs] this formula occurs:
*
* The function is:
* Gray Level = (77 * R + 150 * G + 29 * B + 128)/1024
*
What is the basis for this?
-het
"DOS ... is still a real mode only non-reentrant
interrupt handler, and always will be." - Russell William
Harvey Taylor Meta Media Productions
uunet!van-bc!rsoft!mindlink!Harvey_Taylor
a186@mindlink.UUCPalex@bilver.uucp (Alex Matulich) (02/24/91)
In article <4868@mindlink.UUCP> Harvey_Taylor@mindlink.UUCP (Harvey Taylor) writes: > It seems the maximum greyscale range I can get is 16. Why? It seems > to me I should be able to get 32 using EHB mode. Yes? No? No. The Amiga video hardware only allows 16 intensity levels for the red, green, and blue electron guns in the CRT. You will notice in your palette setup that there are 4 bits per gun, which means 16 levels. Extra half-brite will not help you here. EHB can NOT increase the number of available colors above the 4,096 you already have. EHB will give you a second set of colors that are half the brightness of the first set, but the second set are still within the original 4,096 color range. So, if you already have the 16 gray levels 000,111,222,333,444,555,666,777,888,999,aaa,bbb,ccc,ddd,eee,fff then EHB will give you these "additional" colors which will be repeats of the ones above: 000,000,111,111,222,222,333,333,444,444,555,555,666,666,777,777 The only way I have ever been able to increase the number of gray levels is to use dithering. It's trivial to do with fill masks, and the results are VERY nice in hi-res mode. > In the A2024 docs [in the autodocs] this formula occurs: >* Gray Level = (77 * R + 150 * G + 29 * B + 128)/1024 > What is the basis for this? This formula approximates the NTSC formula for converting color to black & white. -- _ |__ Alex Matulich (alex@bilver.UUCP) /(+__> Unicorn Research Corp, 4621 N Landmark Dr, Orlando, FL 32817 //| \ UUCP: ...uunet!tarpit!bilver!alex ///__) bitnet: IN%"bilver!alex@uunet.uu.net"