Pixel Polizei is a tool for the retro/scene/retroscene artist. It lets you automatically check whether an image conforms to the color limits of a particular oldschool platform and save the result in certain native formats. The underlying idea is that you can use whatever paint program you happen to prefer for creating the images and observe – almost real-time – if you’ve made a mistake somewhere. One more fundamental bit is that the tool is multiplatform unlike many others.
Pixel Polizei is not a paint program or a generic image format converter, even though the aim is to implement at least the most typical file types for the supported platforms. Neither is it meant to be used as a converter for random family photos. You can use it for that purpose too, but the end results won’t be as good as with dedicated tools.

Usage

There’s not much to it: load an image, check whether it’s ok and save it in another format. In the case of errors you can either fix them in your favorite paint program and retry or force the colors to comply. When a piccy is loaded it is automatically converted to the native colorset without dithering, so do that kind of magic elsewhere if needed.
If the loaded png or gif is not of the native resolution, it will be down- or upscaled as necessary, which might or might not produce the desired result. Therefore it’s generally better to do the scaling elsewhere. C-64 multicolor and CPC mode 0 have very flat pixels, so drawing a 320×200 image will probably be easier; every second column will just be discarded.
Checking and forcing can be done automatically. In that case Polizei works according to its name and constantly polls whether you’ve saved the file anew. If there is an updated version, it’s loaded and checked automatically. This way you can quickly find and fix color clashes – keep the Polizei window always visible on another screen or in some corner.
The zoom toggle lets you look at the image closer, and a grid is available for you as well to better see the character block locations. If the platform has a selectable border color, just click on the color selector.
Check out the “palettes” directory to find the exact colors used on each platform. Drawing with those colors ensures that there’s no complications when importing the image.

Amstrad CPC

The CPC is an exceptional 8-bit as you don’t need to care about color clashes: any pixel can be of any color (16 colors in mode 0 and 4 in mode 1). It also has a palette of 27 jolly happy colors to choose from. I found myself wondering what the heck they were thinking when designing the bitmap layout like that.
Supported modes: Mode 0 and 1, with or without overscan (160×200/192×272 and 320×200/384×272).
Supported formats: bin and asm. When copying the files to a dsk image the needed start/load address is $6000 for ordinary images and $100 for overscan pics.
To display the image on an emulator or a real machine, you need to get the file to a floppy – most likely a DSK image. There’s ManageDSK for Windows and iDSK for the rest of us. iDSK probably won’t compile out of the box, but just keep adding #include <stdio.h> to the offending source files until it does. After that you should be able to do this:

iDSK mydisk.dsk -n
iDSK mydisk.dsk -i piccy.bin -t 1 -e 6000 -c 6000

And run the binary from BASIC with:

run"piccy