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AGD converted games - BIGPACKs v2.6

Posted: Wed Nov 27, 2019 4:45 pm
by pser1
Hello,
to help users keep the collection together, I am uploading here a zip whith the whole colection, say 219 games
for each machine and both versions, short and long names
cheers
pere

Re: AGD converted games - BIGPACKs v2.6

Posted: Mon Jun 14, 2021 12:02 am
by lcurtisboyle
Pere - I am trying to convert a Spectrum graphic to a PMODE 4 Dragon/Coco style graphic. I have the interlacing, etc. stuff all figured out fine, but I am finding that the image I am working with seems to switch which bits are black or white depending on which 8x8 tile it is, and I am trying to figure out a rhyme or reason to it. Would it be based on the colors in the attribute section (the last 768 bytes of the Spectrum graphics file), and, if so, how would that be done. From what I see, some tiles are fine, and others are inversed from what they should be (for a black and white image with the tile colors stripped.

Re: AGD converted games - BIGPACKs v2.6

Posted: Mon Jun 14, 2021 6:21 am
by robcfg
Sadly it has to be done manually, as I did with the screens of Aeon.

That said, I can help you if you like to.

Re: AGD converted games - BIGPACKs v2.6

Posted: Mon Jun 14, 2021 4:24 pm
by robcfg
I remembered why some tiles appear to negative.

The bitmap part indicates where the foreground colour and the background colour go inside every 8x8 tile.

But there’s no restriction on what colour is the foreground one or the background one, so without the colour information, the bitmap image can make little sense, as you’ve already seen.

So, what I do is I take the original Spectrum image and then export it to png and from there to Gimp. There I convert it to b/w and add some dithering.

Re: AGD converted games - BIGPACKs v2.6

Posted: Tue Jun 15, 2021 8:29 am
by pser1
lcurtisboyle wrote: Mon Jun 14, 2021 12:02 am Pere - I am trying to convert a Spectrum graphic to a PMODE 4 Dragon/Coco style graphic. I have the interlacing, etc. stuff all figured out fine, but I am finding that the image I am working with seems to switch which bits are black or white depending on which 8x8 tile it is, and I am trying to figure out a rhyme or reason to it. Would it be based on the colors in the attribute section (the last 768 bytes of the Spectrum graphics file), and, if so, how would that be done. From what I see, some tiles are fine, and others are inversed from what they should be (for a black and white image with the tile colors stripped.
Hello!
if you just want to convert a fixed image, it would be enough to 'cut' the Spectrum graphic file stripping out the attribute zone and converting
it into a binary file just adding the header (and trailer for CoCo)
I made a small std C app that does the cutting part. The rest is just copy together fixed chunks
I attach it here for maybe it could be of use for you. The zip contains a windows executable and the source file
Besides I have added a bat file that shows how to use it (in my environment ...)
cheers!
pere
Cutter.zip
(16.96 KiB) Downloaded 260 times

Re: AGD converted games - BIGPACKs v2.6

Posted: Tue Jun 15, 2021 10:55 am
by robcfg
But that generates the problem he’s describing.

It should be easy to do a tool that recreates the original Spectrum image with the right colours, convert it to black and white, and save it.

Re: AGD converted games - BIGPACKs v2.6

Posted: Tue Jun 15, 2021 11:04 am
by pser1
robcfg wrote: Tue Jun 15, 2021 10:55 am But that generates the problem he’s describing.
It should be easy to do a tool that recreates the original Spectrum image with the right colours, convert it to black and white, and save it.
Hello Robert,
All of the AGD games that had an intro screen have been converted the way I have described.
This works perfectly for the PAL Dragons and CoCos
In case you need to run it on a Tano or NTSC CoCo you know that there are big chances for the artifacted colours to appear
The Spectrum resolution is 256x192. If we apply this to a NTSC PMode4 we know it is going to be shown as 128x192 and artifacts
will show up immediately. If this is the case, then there is no other way than manually edit it :-(
cheers!
pere

Ps In artifacted mode we know that every two bits determine the colour of a pixel, so 00, 01, 10, 11 will result in the B/W and the
two additional artifacted colours

Re: AGD converted games - BIGPACKs v2.6

Posted: Tue Jun 15, 2021 12:41 pm
by robcfg
My point is that if you only take the bitmap memory, you don’t get a good image because you can have one color as foreground color on one tile and as background color on the next one, creating the ‘negative squares’ problem.

As I said, it should be easy to create a more consistent result by translating the Spectrum bitmap+attribute memory into a regular image and then converting and dithering it into black and white for the Dragon.

Can you send me a Spectrum image, with its attributes so I can take a look at it?

Re: AGD converted games - BIGPACKs v2.6

Posted: Thu Jul 01, 2021 7:21 pm
by lcurtisboyle
robcfg - your last post described what I was encountering (tiles swapping foreground / background for the same colours on a whim). I changed my converter to allow one to manually select specific tiles to invert, which allowed me to fix the one I was working on (mostly). Unfortunately the project I was doing it for turns out doesn't have enough disk space to always fit a PMODE 4 style graphic, so I stopped working on the "cleanup" phase that Pere was mentioning. But thanks everyone for the help!