Andrew wrote:The same Guru - dithered "by hand" in Photoshop, scaled for QL pixel ratio and loaded in QPC mode 8
Impressive.
Do you know by any chance what algorithm for dithering Photoshop is using?
And could you try to do the same thing to the jinxter bus picture?
Hi Tofro,
You might want to take a look at Ungif. http://www.dilwyn.me.uk/graphics/ungif.zip
It does dithering in mode 4 and 8 and runs on any QL but was used here on QPC2 in mode 8 to make this example.
A DO on the converted image opens a menu to change settings and redo the image.
This size is 512x256, but it can be adjusted to trim the automatic border later.
[img]
Andrew wrote:The same Guru - dithered "by hand" in Photoshop, scaled for QL pixel ratio and loaded in QPC mode 8
Impressive.
Do you know by any chance what algorithm for dithering Photoshop is using?
And could you try to do the same thing to the jinxter bus picture?
Photoshop uses a modified Floyd-Steinberg algorithm - but in our case it doesn't work good when applied to the whole picture.
What i did was: i raised the contrast to maximum then i proportionally scaled the photo to 341x256 to compensate for the different x and y sizes of QL pixels (I also had to add some black to left and right for this) . Then i scaled it to 256x256, reducing only the width. Then i separated the guru from the background and applied a 70% dithering on him. The background was modified by hand, using some patterns and brushes that i created for PI Cole game.
I can do the same for the jinxter bus picture, if you send it to me.
Last edited by Andrew on Sun Nov 17, 2019 9:40 pm, edited 1 time in total.
BSJR wrote:You might want to take a look at Ungif. http://www.dilwyn.me.uk/graphics/ungif.zip
It does dithering in mode 4 and 8 and runs on any QL but was used here on QPC2 in mode 8 to make this example.
A DO on the converted image opens a menu to change settings and redo the image.
This size is 512x256, but it can be adjusted to trim the automatic border later.
[img]CoyoteM8.png[/img]
Hi,
ungif is quite old now, maybe if it was disassembled, it could be updated. I will have a look at this.
While the hand-optimized pictures look all fine and dandy (and could possibly end up with a much better quality as shown), anything that requires the graphics files to be converted up-front, would, unfortunately, also require distributing these converted graphics - as this is not possible due to the legal situation explained above, I'm afraid this is not the way to go, at least until this situation resolves.
I will stick with the straight on-the-fly colour conversion for the moment. And might be looking into the dithvide approach further on.
Would the availability of an afforable SGC successor with decent graphics help software developments like this?
In the sense that, instead of struggling with 8 colors, the software developer could just say "get yourself a 99 £ card for the QL if you want it to look good"?
Or is the software work for MODE 8 mainly fun & challenge, not calling for BBQL hardware upgrades?
Slowly, but steadily, we seem to be gettting somewhere:
Unfortunately, I still have this annoying flickering mentioned in the other thread. I put a delay loop into my keyboard loop, which improved things a bit, but the issue is still there. Today, I have not tested on a real CRT, so it might also be caused by the upscaler.
The horizontal stripes that appear in the picture are not visible in reality - apparently interference with camera exposure time (excuse the crappy pictures taken with my phone)
Last edited by tofro on Tue Dec 03, 2019 11:09 pm, edited 3 times in total.