bad color conversion

Lin Kuei Ominae · Seth **Joined**: 16 Aug 2006 **Location**: Germany

When importing images from clipboard (also using the Import), the color conversion is pretty bad.
Attached is an example.
The attached image shows the original together with the 2 conversion results (one using GIMP to convert into the palette).

Attached ZIP with palette and the SHP showing the difference between SHP Builder color conversion and GIMP palette conversion.
-Frame 1 of SHP has SHP Builder color conversion
-Frame 2 of SHP has GIMP color conversion and then copy into SHP Builder

Especially when you zoom in you can see how SHP builder uses only a very few of the available greens in the palette.
When using GIMP to convert the PNG into the indexed palette, it gives much better results.

While it works using GIMP for single frame things like terraintypes, it's impossible to use it for multi-frame things. So i highly suggest to improve the color to palette conversion of SHP builder.

btw, XCC Mixer creates a similar result as SHP Builder. So this is no option either.

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ApolloTD · Commander **Joined**: 19 Nov 2003

Yeah the algorithm used could be far better to preserve quality.
Alternatively render into sprite sheets and apply palette to it and shp the sheet.

Else I'd just use adobe photoshop/psp etc to batch convert to the pal the individual frames to avoid the quality loss as doubtful Banshee has time to work on shp builder.

Aro · Alcohol Fueled **Joined**: 10 Sep 2006

Sorry to go a little bit off-topic, but those are great!

Banshee · Posted: Wed May 28, 2014 12:05 pm Post subject:

Which color conversion algorithm did you use at OS SHP Builder?

Lin Kuei Ominae · Seth **Joined**: 16 Aug 2006 **Location**: Germany

Banshee wrote:

Which color conversion algorithm did you use at OS SHP Builder?

Oh didn't thought about to test the others.
I was using the default set one "3D RGB Structuralis (fast and very good)"

Just tested
3D RGB Infurium - as bad as Structuralis and almost exactly the same result
3D RGB Full Difference Colour+ - uses more different greens and doesn't has those wide plain colored areas. But hard to tell if it's better just by looking at the conversion of this single image
3D RGB Full Difference - as bad as the others

So only 3D RGB Full Difference Colour+ actually avoided those big plain colored areas.
But none of the 4 comes even close to GIMPs quality.

I also couldn't see any difference between Infurium, Full Difference and Structuralis. At most maybe 2-3 pixel were different colored.

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SHP Artist of Twisted Insurrection: Nod buildings

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X-Mech Calendar (28 Mechs for GDI and Nod)
5 GDI, 5 Nod, 1 Mutant, 1 Scrin unit, 1 GDI building

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Banshee · Posted: Wed May 28, 2014 12:31 pm Post subject:

Infurium and Structuralis are the best color conversion methods in SHP Builder.

All the color conversion methods work locally by trying to find out the color of a single pixel and ignores nearby pixels. I agree that it could have gotten better results if it considered the transition of the current pixel with the nearby pixels. But I don't think that the result is bad at all.

Using more shades of green in this situation doesn't mean that these shades of green are the closest colors to the original ones. I think that Structuralis did better than GIMP in this point of view, but the color transitions in GIMP were closer to the original one.

Lin Kuei Ominae · Seth **Joined**: 16 Aug 2006 **Location**: Germany

yeah mathematic view <> human view

While the mathematic of SHP Builder might be correct, i think the more colors of GIMP result in a higher detail in the result.

In some cases the SHP Builder conversion also came to quite strange results: it used some very bright green/yellows, while a slightly darker pure green was much closer to the original.
If you have time, maybe you could implement the DeltaE2000 formula that i used in TMP Shop. This ignores surrounding pixel too and just goes by best matching color for every single pixel.

_________________
SHP Artist of Twisted Insurrection: Nod buildings

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X-Mech Calendar (28 Mechs for GDI and Nod)
5 GDI, 5 Nod, 1 Mutant, 1 Scrin unit, 1 GDI building

Tools
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Banshee · Posted: Wed May 28, 2014 1:17 pm Post subject:

I'll put DeltaE2000 in my list of things to do to OS SHP Builder in a later time. Right now, my focus is my thesis using VXLSE III.

E1 Elite · General **Joined**: 28 May 2013

It might be the dithering rather than the color difference algorithms which is available in GIMP
with various options. Dithering in SHP Builder is a checkbox on last tab Extra Settings.

I don't have GIMP installed but saw here:
http://docs.gimp.org/en/gimp-image-convert-indexed.html