diff options
Diffstat (limited to 'src/pkg/image/image.go')
| -rw-r--r-- | src/pkg/image/image.go | 17 |
1 files changed, 7 insertions, 10 deletions
diff --git a/src/pkg/image/image.go b/src/pkg/image/image.go index f4ac823e1..3ac7d4eb2 100644 --- a/src/pkg/image/image.go +++ b/src/pkg/image/image.go @@ -185,21 +185,18 @@ func (p PalettedColorModel) Convert(c Color) Color { if len(p) == 0 { return nil } - // TODO(nigeltao): Revisit the "pick the palette color which minimizes sum-squared-difference" - // algorithm when the premultiplied vs unpremultiplied issue is resolved. - // Currently, we only compare the R, G and B values, and ignore A. cr, cg, cb, _ := c.RGBA() - // Shift by 17 bits to avoid potential uint32 overflow in sum-squared-difference. - cr >>= 17 - cg >>= 17 - cb >>= 17 + // Shift by 1 bit to avoid potential uint32 overflow in sum-squared-difference. + cr >>= 1 + cg >>= 1 + cb >>= 1 result := Color(nil) bestSSD := uint32(1<<32 - 1) for _, v := range p { vr, vg, vb, _ := v.RGBA() - vr >>= 17 - vg >>= 17 - vb >>= 17 + vr >>= 1 + vg >>= 1 + vb >>= 1 dr, dg, db := diff(cr, vr), diff(cg, vg), diff(cb, vb) ssd := (dr * dr) + (dg * dg) + (db * db) if ssd < bestSSD { |