← back to index

IDCT prescale + Lanczos3  vs  pure Lanczos3

Input: Zonotrichia_leucophrys_CT2.jpg (1728×2592). --idct-min-factor 2.5. Images render at intrinsic pixel size — no CSS scaling.
Firefox would take the IDCT path on this image — 1728 × 2592 is a whole number of MCU blocks (16 × 16). The renders below reflect what would ship.
Space or click the button toggles every pair at once. Click a single image to toggle just that pair. Hold Shift while clicking the toolbar button to swap continuously.
1/2 barely target 346 × 518 · IDCT 1/2 → 864×1296 · Lanczos ratio ˜ 2.50×
IDCT pure
IDCT ● click to flick PURE ● click to flick
IDCT+Lanczos ⇄ pure Lanczos @ 346×518
diff abs diff ×10
pixel delta, amplified 10×
1/2 heavy target 173 × 260 · IDCT 1/2 → 864×1296 · Lanczos ratio ˜ 4.99×
IDCT pure
IDCT ● click to flick PURE ● click to flick
IDCT+Lanczos ⇄ pure Lanczos @ 173×260
diff abs diff ×10
pixel delta, amplified 10×
1/4 barely target 173 × 259 · IDCT 1/4 → 432×648 · Lanczos ratio ˜ 2.50×
IDCT pure
IDCT ● click to flick PURE ● click to flick
IDCT+Lanczos ⇄ pure Lanczos @ 173×259
diff abs diff ×10
pixel delta, amplified 10×
1/4 heavy target 87 × 130 · IDCT 1/4 → 432×648 · Lanczos ratio ˜ 4.98×
IDCT pure
IDCT ● click to flick PURE ● click to flick
IDCT+Lanczos ⇄ pure Lanczos @ 87×130
diff abs diff ×10
pixel delta, amplified 10×
1/8 barely target 86 × 130 · IDCT 1/8 → 216×324 · Lanczos ratio ˜ 2.51×
IDCT pure
IDCT ● click to flick PURE ● click to flick
IDCT+Lanczos ⇄ pure Lanczos @ 86×130
diff abs diff ×10
pixel delta, amplified 10×
1/8 heavy target 43 × 65 · IDCT 1/8 → 216×324 · Lanczos ratio ˜ 5.02×
IDCT pure
IDCT ● click to flick PURE ● click to flick
IDCT+Lanczos ⇄ pure Lanczos @ 43×65
diff abs diff ×10
pixel delta, amplified 10×