I apologize, most sincerely, to those of you who have traveled to this message under the impression that it was, in any way, connected with the discussion of the new Scandoubler. This was due to an or the error in the scripting stage of the discussions title. This thread is actually a forum for alexh to joke about anyone not fully versed in indexed colour.
We apologize for the previous apology. This apology was unnecessary and appeared on this website owing to an administrative error. This thread is not, as stated in the previous apology, a forum for alexh to joke about anyone not fully versed in indexed colour, but a thread devoted to -- and hereafter totally taken up with -- the...
alexh wrote:
Crap not another person who doesnt understand the difference between palettes entries vs colour depth ;-)
Edit: Oh, I am so sorry! Sincerest apologies. I just noticed you were an American. You dont have sarcasm do you? ;-)
Oh, we get sarcasm - just fine across the ruddy pond. ;-) I just must have forgotten that dry British humor. Especially, referencing conversations or situations that the comedic receiver may have no actual form of reference to. ;-)
In fact I think the King's English would say that your statement wasn't sarcastic at all -
"Sarcasm is stating the opposite of an intended meaning especially in order to sneeringly, slyly, jest or mock a person, situation or thing. It is strongly associated with irony, with some definitions classifying it as a type of verbal irony intended to insult or wound. An example of sarcasm is using "that's fantastic" to mean "that's awful"."
But anyway, apology accepted.
Nlandas wrote:
Indexed color was always confusing to me. I roughly understand the the on screen palette of colors is selected from a "master" 24-bit palette and can be changed at any time affecting the whole screen.
alexh wrote:
Perfect description.
;-) Uh oh, I hope that wasn't sarcasm that time. ;-)
Nlandas wrote:
However, I never understood how a 16-bit "master" palette couldn't be changed on the fly as well to accommodate the actual colors selected for the smaller on screen palette.
alexh wrote:
The scandoubler and the AGA chipset are not coupled in any way. The graphics have already been converted from 8-bit indexed to 24-bit direct colour by the time they arrive at the scandoubler. It does not matter that there are only 256 different colours, there is no way the scandoubler can know this, or do anything about it if it did!
A 16-bit "master" palette as you call it can never display some of the colours contained in a 24-bit master palette, the information is lost.
That makes perfect sense. Thank you, for filling in the gaps in my understanding alexh. I appreciate your repeating yourself.
However, would it be possible to write a software driver and pass the original "master" palette information to the scandoubler via serial cable to the scandoubler? The scan doubler could then map the used areas of the 24-bit master palette to the 16-bit palette to correct for the smaller master palette space. Of course it doesn't sound like this would allow for a cheaper implementation than using even the less common 24-bit chips you speak of below.
Does Amiga.org have a FAQ with things like this. I've been here long enough to see the topic discussed and if the different descriptions were pulled together into an FAQ. It would make it easier for you and others to just be able to refer to the FAQ.I think we all also see how to hook my Amiga to a VGA monitor at least once a month.
Nlandas wrote:
The AL875 chip already outputs 24 bit.
alexh wrote:
The AL875 is an unremarkable chip. It is just a 3 channel ADC. There are lots of similar chips, from other manufacturers.
That's probably why Roy chose it.
Nlandas wrote:
The bottle neck is the AL250. If I can find a 24 bit replacement who knows
alexh wrote:
Unfortunately when the colourspace is Chroma/Luma (found in CVBS / SVideo)16-bits is more than enough for accurate colour representation, this is why most chips just have 16-bit inputs :-( You're gonna find it difficult to find a chip which is as cheap as the AL250A or as integrated for the money. You could easily make your own 24-bit scandoubler with a CPLD and some RAM (akin to the internal DCE Flicker Magic) but the cost would go up to $120+
That sounds good to me. I don't know about you but I'd be happy to pay $120 for a reasonable quality 24-bit AGA RGB scandoubler/flicker fixer. $900USD for a Toastscan or $500USD for a Piscasso IV, just isn't going to happen. No matter how much I love my Amiga.
-Nyle
