Mr Tillman CS

Lossy Bench

Two ways of throwing data away, on the same 600 × 420 bitmap. Drag the slider and watch the file size fall. OCR J277 · 1.2.5

Image
View
Original 738 KB
16 colours —

Pixel count unchanged · 600 × 420 = 252,000 pixels, before and after

The palette 16 colours, chosen from this image
16 colours per pixel 4 bits
Uncompressed bitmap 738 KB 600 × 420 × 24 bits ÷ 8
After compression — —
Saved — of the uncompressed file

—

Inspector ×8 Click or drag on either image above to move the box
Original
Result

Colour depth uses a median-cut palette built from this image, the way a GIF encoder does. JPEG quality runs the image through the browser's real JPEG encoder, so the byte counts and the artefacts are genuine, not simulated. "What was lost" is the pixel-by-pixel difference, amplified ×8 so it is visible at all.