Posted By
IstvanV
on 2008-08-23
08:04:28
|  Re: So I want to do plus/4 gfx...
> Sometimes (interestingely) the preview have better results, than in the Emu. (maybe my monitor settings).
The preview of the image converter is identical to plus4emu in OpenGL mode with the settings shown here http://www.sharemation.com/IstvanV/p4dispcfg1.png for all modes other than interlaced hires FLI, in which case the settings are as shown here: http://www.sharemation.com/IstvanV/p4dispcfg2.png.
Note the quality setting of 3, which enables the emulation of PAL filters and scanline shading (this requires an OpenGL 2.0 compatible video card and drivers).
The image conversion in p4fliconv is also always optimized for the palette of the plus4emu version with which the converter is distributed.
> - Resize to 320x200. Use the Lacnzos method
The image scaling in p4fliconv first resizes the input image to 640x400 (at least for simple hires/multicolor modes; in all cases, however, the size of a character at the intermediate resolution is 16x16 pixels) with anti-aliased sinc interpolation, and then downsamples that to the actual output resolution with simple box filtering. Therefore, you should pixelize the image to 640x400 (4x2 pixels in multicolor mode), and not 320x200 if you want to avoid additional image scaling artifacts in the converter.
> I found GIF reducing the overall color palette too reduced
Using the GIF format can actually be useful for pixel exact conversion, because the converter treats it in a special way if the colormap matches the Plus/4 colormap (with all colors at the correct indices, and no colors removed to "optimize" the palette): the sinc interpolation is replaced with nearest-neighbor "interpolation", and the image palette is replaced to match the internal floating point YUV colormap of the converter exactly, to avoid palettization artifacts.
|
