Convert JPEG to SCR

A ZX Spectrum emulator, graphics editor, or hardware archive may require a JPEG as a native .scr screen file. The conversion creates a fixed ZX Spectrum display image, not a Windows screensaver executable.

What the JPEG format is

JPEG is a lossy raster-image format used for photographs and continuous-tone images. Cameras, smartphones, scanners, web browsers, and editors such as Adobe Photoshop, GIMP, and Affinity Photo commonly create or export .jpg and .jpeg files. JPEG supports millions of colors and adjustable compression, but repeated saving can remove detail and create block artifacts.

What the SCR format is

In graphics software, .scr commonly denotes a ZX Spectrum screen file. A standard file contains 6,912 bytes: 6,144 bytes of bitmap data for a 256 × 192 display and 768 attribute bytes. Each 8 × 8 pixel cell has an ink color, a paper color, a shared brightness setting, and a flash flag.

SCR is used by ZX Spectrum emulators, retro-game graphics editors, demoscene tools, and archives of original Spectrum graphics. Its fixed size matches the computer's display memory and makes files very small, but each cell can use only two color roles from the Spectrum palette. The extension is also used for unrelated formats, including Windows screensavers, so the receiving application must specifically expect a ZX Spectrum SCR file.

How to convert a JPEG to SCR

A dedicated ZX Spectrum graphics editor is the safest option because it can perform per-cell attribute conversion rather than merely reducing the whole image to a generic palette. Open the JPEG in a tool such as ZX Paintbrush, set or crop the canvas to 256 × 192 pixels, choose its ZX Spectrum color or attribute-clash conversion, inspect the preview, and use File → Save as or the equivalent SCR export command. Importing a PNG created from the JPEG first can avoid another JPEG re-save.

ImageMagick can be used when its installation includes an SCR encoder. Check the available formats with:

magick -list format

Look for an entry named SCR with write permission, such as SCR RW. If it is present, this command crops the image without distortion, converts it to sRGB, reduces the color count, and requests SCR output:

magick input.jpg -resize 256x192^ -gravity center -extent 256x192 -colorspace sRGB -colors 16 -dither FloydSteinberg SCR:output.scr

The ^ fills the target dimensions and crops excess content. Replace it with -resize 256x192! to stretch the image instead. Open the result in a ZX Spectrum emulator or editor and check every cell; a generic quantizer does not guarantee visually good ink and paper assignments. If ImageMagick reports that SCR is unsupported or read-only, use a ZX Spectrum editor instead of renaming a PNG or JPEG.

Generic online image converters are usually unsuitable because many do not support ZX Spectrum SCR, while some interpret .scr as a Windows screensaver. An online service is usable only when it explicitly identifies the output as a ZX Spectrum 256 × 192 SCR file and produces a 6,912-byte result. Verify the downloaded file in an emulator; a renamed image or a different SCR variant is not compatible.

Quality and compatibility limitations

The conversion discards the JPEG's original resolution, broad color range, metadata, transparency, and any layers. A photograph must be reduced to 256 × 192 pixels and mapped to the Spectrum palette. Within each 8 × 8 cell, adjacent pixels cannot freely use different foreground and background colors, causing attribute clash around text, edges, and detailed subjects.

Floyd–Steinberg dithering can suggest intermediate tones but may produce noisy patterns. Disabling dithering gives harder color boundaries and can work better for logos, sprites, and line art. Use the highest-quality original available before conversion, because a previously compressed JPEG adds artifacts that become more visible after resizing and palette reduction.