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#20105 - 11/10/2000 16:03 Exact Gray Values?
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31578
Loc: Seattle, WA
I'm finally knuckling down and writing my empeg logo editor. It's coming along nicely.

One of its features is that it accepts any color-depth image as an input, then color-reduces it to the four colors of the empeg display.

Although I've eyeballed the gray levels, it would be nice to know exactly what percentage the two shades of gray are. Assuming that "off" is "0" and that the brightest pixel is "full on" or "255", then where exactly do the two shades of gray fall in a 0-255 scale?

I seem to recall that this was posted elsewhere, but I'm not sure what terms to search on right now...

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Tony Fabris
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#20106 - 11/10/2000 16:14 Re: Exact Gray Values? [Re: tfabris]
ricin
veteran

Registered: 19/06/2000
Posts: 1495
Loc: US: CA
Is this what you're looking for?

Pixel Value........Intensity..............Modulation Rate

0..................0%.....................0
1..................11.1%..................1/9
2..................20%....................1/5
3..................100%...................1






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Donato
MkII/Blue/40GB/080000565


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Donato
MkII/080000565
MkIIa/010101253
ricin.us

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#20107 - 11/10/2000 16:24 Re: Exact Gray Values? [Re: ricin]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31578
Loc: Seattle, WA
Thanks. I'll paste that into my code comments now and get to work with Windows Calculator to turn that into 0-255 numbers.

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Tony Fabris
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Tony Fabris

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#20108 - 11/10/2000 17:07 Re: Exact Gray Values? [Re: tfabris]
alear
enthusiast

Registered: 05/07/2000
Posts: 301
Loc: Montana, USA, Bozeman
Can't wait to see how it turns out Tony. How long will it take you assuming you still work and sleep?

The ability to use any color depth picture will be cool.

A logo editor should be put on the empeg software disc.

Alex Lear
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Alex Lear

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#20109 - 11/10/2000 18:46 Re: Exact Gray Values? [Re: alear]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31578
Loc: Seattle, WA
How long will it take you assuming you still work and sleep?

I anticipate having something usable sometime next week.

Of course, the above is an estimate from a programmer, which you can't trust. I have a rule of thumb: Whatever estimate a programmer gives you, double it and increment the units. For example, I told you one week, so by my rule of thumb you should expect it within two months.

It shouldn't be that bad, though, I'm doing it in VB (after spending a day struggling with Device Contexts and memory allocations under C++ and giving up), so it shouldn't take too long. Actually, I've done graphics stuff in C before, it's just that I decided the additional coding complexity wasn't worth the performance gains since these are only small 128x32 images.

I'll probably convert the download.c code into a DLL and call that from my VB program to get the transfers done.


The ability to use any color depth picture will be cool.

I've already got the color reduction working (hard cutoffs only, no dithering). Turns out that the values I asked for at the top of this thread look completely wrong on the Windows screen, so I had to hand-estimate my cutoffs anyhow.


A logo editor should be put on the empeg software disc.

Even if one were, I dunno if this'd be the appropriate one. It's written in VB, and a really old version of VB at that. But hopefully it'll work, only time will tell if it's even any good.

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Tony Fabris
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#20110 - 12/10/2000 04:58 Re: Exact Gray Values? [Re: tfabris]
rob
carpal tunnel

Registered: 21/05/1999
Posts: 5335
Loc: Cambridge UK
This was one of the questions in the empeg geek quiz at Amersfoort - you'd have lost two points!

Rob


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#20111 - 12/10/2000 05:12 Re: Exact Gray Values? [Re: rob]
fvgestel
old hand

Registered: 12/08/2000
Posts: 702
Loc: Netherlands
Don't worry bout that Tony,
I scored only 4 out of 15 ( I believe it was 15 )

Frank van Gestel
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