Day 003 — CRT//IMG Monochrome Processor

Interactive image processor that converts any image into a monochrome CRT monitor aesthetic. Drag & drop an image, tweak the parameters, download the result.

Features

• 4 color palettes: Phosphor Green, Amber, Paper White, Cyan
• Adjustments: Brightness, contrast, gamma, saturation
• CRT effects: Scanlines, bloom, noise, pixel scaling
• Dithering: Floyd-Steinberg dithering for authentic 1-bit look
• Halftone: Dot-pattern alternative to dithering
• Resample mode: Dithers at full resolution, multi-step downscales, and re-thresholds for a clean 2-color result with organic line structures
• Invert toggle
• Luminance histogram for real-time feedback
• Indexed PNG export: 1-bit palette PNG with minimal file size

How it works

Images are loaded into a Canvas, converted to luminance values, and processed through a pipeline of brightness/contrast/gamma adjustments. Floyd-Steinberg error diffusion dithering quantizes the result to two tones. The output is colorized with the selected phosphor palette and composited with scanlines, bloom, and noise effects.

In resample mode, the image is dithered at full source resolution, scanlines are baked into the binary pixels, then multi-step downscaled and re-thresholded — producing clean 2-color output with natural horizontal structures from the dithering algorithm itself.

Export uses an inline indexed PNG encoder (1-bit palette, zlib via CompressionStream) for tiny file sizes.

All processing happens client-side — no data leaves the browser.

Controls

• Drag & drop or click to load an image
• Adjust sliders in the sidebar
• Toggle dithering/halftone/invert/resample
• Click Download PNG to export as indexed PNG