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Indexed colour palette Image does anyone have one of mega drive colours?

#16 User is offline Shadow Hog 

Posted 07 December 2015 - 09:53 PM

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Is that any different from an H-blank? Y'know, that very brief period between the CRT monitor finishing one scanline and starting the next.

#17 User is offline rata 

Posted 07 December 2015 - 11:11 PM

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Oh, of course... what a dumbass I am. So, what's the real deal with the colours? Is it then 61 the maximium per scanline?
Also, can shadow colours get mixed with normal ones, or the whole mode has to be changed? Can it be done in a single frame, for example, to simulate glare?

#18 User is offline Korama 

Posted 07 December 2015 - 11:46 PM

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View PostShadow Hog, on 07 December 2015 - 09:53 PM, said:

Is that any different from an H-blank? Y'know, that very brief period between the CRT monitor finishing one scanline and starting the next.

It's the same. A horizontal interrupt (HInt) is triggered at the start of each H-blank.


View Postrata, on 07 December 2015 - 11:11 PM, said:

Oh, of course... what a dumbass I am. So, what's the real deal with the colours? Is it then 61 the maximium per scanline?
Also, can shadow colours get mixed with normal ones, or the whole mode has to be changed? Can it be done in a single frame, for example, to simulate glare?

Yes, it's pretty much 61 per scanline, but you can only change a limited amount of those from one scanline to the next, if I remember correctly.
I don't understand what you mean with the shadow colors. Shadow/highlight mode is either active or not. If it is active, it does influence the colors in combination with certain sprites and pattern priority bits. You can play around with this old program of mine to test it.

#19 User is offline MainMemory 

Posted 08 December 2015 - 01:07 AM

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Actually, the MD only generates a horizontal interrupt every Nth scanline from the top of the screen/previous H-Int, with N being the value in VDP register $A.
This post has been edited by MainMemory: 08 December 2015 - 01:08 AM

#20 User is offline rata 

Posted 08 December 2015 - 11:59 AM

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Usually when tech members talk I just don't understand a thing, but I did learn something today, as small as it is. Thank you very much both of you.

#21 User is offline LocalH 

Posted 08 December 2015 - 12:31 PM

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Actually, almost every such MD "palette" is inaccurate to actual system output. Over at Spritesmind, Tiido did some work measuring the MD's actual output levels (not by visually examining the output, but by measuring it on an oscilloscope). Turns out the MD's video output is nonlinear.

Quote

Old incorrect linear levels :
Normal : 0 36 72 108 144 180 216 252/255
Shadow : 0 18 36 54 72 90 108 126
HiLite : 126 144 162 180 198 216 234 252/255

Nonlinear levels derived from hardware measurements :
Normal : 0 52 87 116 144 172 206 255
Shadow : 0 29 52 70 87 101 116 130
HiLite : 130 144 158 172 187 206 228 255


Edit: Didn't see Korama had linked to this up above.
This post has been edited by LocalH: 08 December 2015 - 12:33 PM

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