mirror of
https://github.com/42wim/matterbridge
synced 2024-11-07 09:20:23 +00:00
300 lines
8.2 KiB
Go
300 lines
8.2 KiB
Go
|
// Copyright 2014 The Go Authors. All rights reserved.
|
||
|
|
// Use of this source code is governed by a BSD-style
|
||
|
|
// license that can be found in the LICENSE file.
|
||
|
|
|
||
|
|
package vp8l
|
||
|
|
|
||
|
|
// This file deals with image transforms, specified in section 3.
|
||
|
|
|
||
|
|
// nTiles returns the number of tiles needed to cover size pixels, where each
|
||
|
|
// tile's side is 1<<bits pixels long.
|
||
|
|
func nTiles(size int32, bits uint32) int32 {
|
||
|
|
return (size + 1<<bits - 1) >> bits
|
||
|
|
}
|
||
|
|
|
||
|
|
const (
|
||
|
|
transformTypePredictor = 0
|
||
|
|
transformTypeCrossColor = 1
|
||
|
|
transformTypeSubtractGreen = 2
|
||
|
|
transformTypeColorIndexing = 3
|
||
|
|
nTransformTypes = 4
|
||
|
|
)
|
||
|
|
|
||
|
|
// transform holds the parameters for an invertible transform.
|
||
|
|
type transform struct {
|
||
|
|
// transformType is the type of the transform.
|
||
|
|
transformType uint32
|
||
|
|
// oldWidth is the width of the image before transformation (or
|
||
|
|
// equivalently, after inverse transformation). The color-indexing
|
||
|
|
// transform can reduce the width. For example, a 50-pixel-wide
|
||
|
|
// image that only needs 4 bits (half a byte) per color index can
|
||
|
|
// be transformed into a 25-pixel-wide image.
|
||
|
|
oldWidth int32
|
||
|
|
// bits is the log-2 size of the transform's tiles, for the predictor
|
||
|
|
// and cross-color transforms. 8>>bits is the number of bits per
|
||
|
|
// color index, for the color-index transform.
|
||
|
|
bits uint32
|
||
|
|
// pix is the tile values, for the predictor and cross-color
|
||
|
|
// transforms, and the color palette, for the color-index transform.
|
||
|
|
pix []byte
|
||
|
|
}
|
||
|
|
|
||
|
|
var inverseTransforms = [nTransformTypes]func(*transform, []byte, int32) []byte{
|
||
|
|
transformTypePredictor: inversePredictor,
|
||
|
|
transformTypeCrossColor: inverseCrossColor,
|
||
|
|
transformTypeSubtractGreen: inverseSubtractGreen,
|
||
|
|
transformTypeColorIndexing: inverseColorIndexing,
|
||
|
|
}
|
||
|
|
|
||
|
|
func inversePredictor(t *transform, pix []byte, h int32) []byte {
|
||
|
|
if t.oldWidth == 0 || h == 0 {
|
||
|
|
return pix
|
||
|
|
}
|
||
|
|
// The first pixel's predictor is mode 0 (opaque black).
|
||
|
|
pix[3] += 0xff
|
||
|
|
p, mask := int32(4), int32(1)<<t.bits-1
|
||
|
|
for x := int32(1); x < t.oldWidth; x++ {
|
||
|
|
// The rest of the first row's predictor is mode 1 (L).
|
||
|
|
pix[p+0] += pix[p-4]
|
||
|
|
pix[p+1] += pix[p-3]
|
||
|
|
pix[p+2] += pix[p-2]
|
||
|
|
pix[p+3] += pix[p-1]
|
||
|
|
p += 4
|
||
|
|
}
|
||
|
|
top, tilesPerRow := 0, nTiles(t.oldWidth, t.bits)
|
||
|
|
for y := int32(1); y < h; y++ {
|
||
|
|
// The first column's predictor is mode 2 (T).
|
||
|
|
pix[p+0] += pix[top+0]
|
||
|
|
pix[p+1] += pix[top+1]
|
||
|
|
pix[p+2] += pix[top+2]
|
||
|
|
pix[p+3] += pix[top+3]
|
||
|
|
p, top = p+4, top+4
|
||
|
|
|
||
|
|
q := 4 * (y >> t.bits) * tilesPerRow
|
||
|
|
predictorMode := t.pix[q+1] & 0x0f
|
||
|
|
q += 4
|
||
|
|
for x := int32(1); x < t.oldWidth; x++ {
|
||
|
|
if x&mask == 0 {
|
||
|
|
predictorMode = t.pix[q+1] & 0x0f
|
||
|
|
q += 4
|
||
|
|
}
|
||
|
|
switch predictorMode {
|
||
|
|
case 0: // Opaque black.
|
||
|
|
pix[p+3] += 0xff
|
||
|
|
|
||
|
|
case 1: // L.
|
||
|
|
pix[p+0] += pix[p-4]
|
||
|
|
pix[p+1] += pix[p-3]
|
||
|
|
pix[p+2] += pix[p-2]
|
||
|
|
pix[p+3] += pix[p-1]
|
||
|
|
|
||
|
|
case 2: // T.
|
||
|
|
pix[p+0] += pix[top+0]
|
||
|
|
pix[p+1] += pix[top+1]
|
||
|
|
pix[p+2] += pix[top+2]
|
||
|
|
pix[p+3] += pix[top+3]
|
||
|
|
|
||
|
|
case 3: // TR.
|
||
|
|
pix[p+0] += pix[top+4]
|
||
|
|
pix[p+1] += pix[top+5]
|
||
|
|
pix[p+2] += pix[top+6]
|
||
|
|
pix[p+3] += pix[top+7]
|
||
|
|
|
||
|
|
case 4: // TL.
|
||
|
|
pix[p+0] += pix[top-4]
|
||
|
|
pix[p+1] += pix[top-3]
|
||
|
|
pix[p+2] += pix[top-2]
|
||
|
|
pix[p+3] += pix[top-1]
|
||
|
|
|
||
|
|
case 5: // Average2(Average2(L, TR), T).
|
||
|
|
pix[p+0] += avg2(avg2(pix[p-4], pix[top+4]), pix[top+0])
|
||
|
|
pix[p+1] += avg2(avg2(pix[p-3], pix[top+5]), pix[top+1])
|
||
|
|
pix[p+2] += avg2(avg2(pix[p-2], pix[top+6]), pix[top+2])
|
||
|
|
pix[p+3] += avg2(avg2(pix[p-1], pix[top+7]), pix[top+3])
|
||
|
|
|
||
|
|
case 6: // Average2(L, TL).
|
||
|
|
pix[p+0] += avg2(pix[p-4], pix[top-4])
|
||
|
|
pix[p+1] += avg2(pix[p-3], pix[top-3])
|
||
|
|
pix[p+2] += avg2(pix[p-2], pix[top-2])
|
||
|
|
pix[p+3] += avg2(pix[p-1], pix[top-1])
|
||
|
|
|
||
|
|
case 7: // Average2(L, T).
|
||
|
|
pix[p+0] += avg2(pix[p-4], pix[top+0])
|
||
|
|
pix[p+1] += avg2(pix[p-3], pix[top+1])
|
||
|
|
pix[p+2] += avg2(pix[p-2], pix[top+2])
|
||
|
|
pix[p+3] += avg2(pix[p-1], pix[top+3])
|
||
|
|
|
||
|
|
case 8: // Average2(TL, T).
|
||
|
|
pix[p+0] += avg2(pix[top-4], pix[top+0])
|
||
|
|
pix[p+1] += avg2(pix[top-3], pix[top+1])
|
||
|
|
pix[p+2] += avg2(pix[top-2], pix[top+2])
|
||
|
|
pix[p+3] += avg2(pix[top-1], pix[top+3])
|
||
|
|
|
||
|
|
case 9: // Average2(T, TR).
|
||
|
|
pix[p+0] += avg2(pix[top+0], pix[top+4])
|
||
|
|
pix[p+1] += avg2(pix[top+1], pix[top+5])
|
||
|
|
pix[p+2] += avg2(pix[top+2], pix[top+6])
|
||
|
|
pix[p+3] += avg2(pix[top+3], pix[top+7])
|
||
|
|
|
||
|
|
case 10: // Average2(Average2(L, TL), Average2(T, TR)).
|
||
|
|
pix[p+0] += avg2(avg2(pix[p-4], pix[top-4]), avg2(pix[top+0], pix[top+4]))
|
||
|
|
pix[p+1] += avg2(avg2(pix[p-3], pix[top-3]), avg2(pix[top+1], pix[top+5]))
|
||
|
|
pix[p+2] += avg2(avg2(pix[p-2], pix[top-2]), avg2(pix[top+2], pix[top+6]))
|
||
|
|
pix[p+3] += avg2(avg2(pix[p-1], pix[top-1]), avg2(pix[top+3], pix[top+7]))
|
||
|
|
|
||
|
|
case 11: // Select(L, T, TL).
|
||
|
|
l0 := int32(pix[p-4])
|
||
|
|
l1 := int32(pix[p-3])
|
||
|
|
l2 := int32(pix[p-2])
|
||
|
|
l3 := int32(pix[p-1])
|
||
|
|
c0 := int32(pix[top-4])
|
||
|
|
c1 := int32(pix[top-3])
|
||
|
|
c2 := int32(pix[top-2])
|
||
|
|
c3 := int32(pix[top-1])
|
||
|
|
t0 := int32(pix[top+0])
|
||
|
|
t1 := int32(pix[top+1])
|
||
|
|
t2 := int32(pix[top+2])
|
||
|
|
t3 := int32(pix[top+3])
|
||
|
|
l := abs(c0-t0) + abs(c1-t1) + abs(c2-t2) + abs(c3-t3)
|
||
|
|
t := abs(c0-l0) + abs(c1-l1) + abs(c2-l2) + abs(c3-l3)
|
||
|
|
if l < t {
|
||
|
|
pix[p+0] += uint8(l0)
|
||
|
|
pix[p+1] += uint8(l1)
|
||
|
|
pix[p+2] += uint8(l2)
|
||
|
|
pix[p+3] += uint8(l3)
|
||
|
|
} else {
|
||
|
|
pix[p+0] += uint8(t0)
|
||
|
|
pix[p+1] += uint8(t1)
|
||
|
|
pix[p+2] += uint8(t2)
|
||
|
|
pix[p+3] += uint8(t3)
|
||
|
|
}
|
||
|
|
|
||
|
|
case 12: // ClampAddSubtractFull(L, T, TL).
|
||
|
|
pix[p+0] += clampAddSubtractFull(pix[p-4], pix[top+0], pix[top-4])
|
||
|
|
pix[p+1] += clampAddSubtractFull(pix[p-3], pix[top+1], pix[top-3])
|
||
|
|
pix[p+2] += clampAddSubtractFull(pix[p-2], pix[top+2], pix[top-2])
|
||
|
|
pix[p+3] += clampAddSubtractFull(pix[p-1], pix[top+3], pix[top-1])
|
||
|
|
|
||
|
|
case 13: // ClampAddSubtractHalf(Average2(L, T), TL).
|
||
|
|
pix[p+0] += clampAddSubtractHalf(avg2(pix[p-4], pix[top+0]), pix[top-4])
|
||
|
|
pix[p+1] += clampAddSubtractHalf(avg2(pix[p-3], pix[top+1]), pix[top-3])
|
||
|
|
pix[p+2] += clampAddSubtractHalf(avg2(pix[p-2], pix[top+2]), pix[top-2])
|
||
|
|
pix[p+3] += clampAddSubtractHalf(avg2(pix[p-1], pix[top+3]), pix[top-1])
|
||
|
|
}
|
||
|
|
p, top = p+4, top+4
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return pix
|
||
|
|
}
|
||
|
|
|
||
|
|
func inverseCrossColor(t *transform, pix []byte, h int32) []byte {
|
||
|
|
var greenToRed, greenToBlue, redToBlue int32
|
||
|
|
p, mask, tilesPerRow := int32(0), int32(1)<<t.bits-1, nTiles(t.oldWidth, t.bits)
|
||
|
|
for y := int32(0); y < h; y++ {
|
||
|
|
q := 4 * (y >> t.bits) * tilesPerRow
|
||
|
|
for x := int32(0); x < t.oldWidth; x++ {
|
||
|
|
if x&mask == 0 {
|
||
|
|
redToBlue = int32(int8(t.pix[q+0]))
|
||
|
|
greenToBlue = int32(int8(t.pix[q+1]))
|
||
|
|
greenToRed = int32(int8(t.pix[q+2]))
|
||
|
|
q += 4
|
||
|
|
}
|
||
|
|
red := pix[p+0]
|
||
|
|
green := pix[p+1]
|
||
|
|
blue := pix[p+2]
|
||
|
|
red += uint8(uint32(greenToRed*int32(int8(green))) >> 5)
|
||
|
|
blue += uint8(uint32(greenToBlue*int32(int8(green))) >> 5)
|
||
|
|
blue += uint8(uint32(redToBlue*int32(int8(red))) >> 5)
|
||
|
|
pix[p+0] = red
|
||
|
|
pix[p+2] = blue
|
||
|
|
p += 4
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return pix
|
||
|
|
}
|
||
|
|
|
||
|
|
func inverseSubtractGreen(t *transform, pix []byte, h int32) []byte {
|
||
|
|
for p := 0; p < len(pix); p += 4 {
|
||
|
|
green := pix[p+1]
|
||
|
|
pix[p+0] += green
|
||
|
|
pix[p+2] += green
|
||
|
|
}
|
||
|
|
return pix
|
||
|
|
}
|
||
|
|
|
||
|
|
func inverseColorIndexing(t *transform, pix []byte, h int32) []byte {
|
||
|
|
if t.bits == 0 {
|
||
|
|
for p := 0; p < len(pix); p += 4 {
|
||
|
|
i := 4 * uint32(pix[p+1])
|
||
|
|
pix[p+0] = t.pix[i+0]
|
||
|
|
pix[p+1] = t.pix[i+1]
|
||
|
|
pix[p+2] = t.pix[i+2]
|
||
|
|
pix[p+3] = t.pix[i+3]
|
||
|
|
}
|
||
|
|
return pix
|
||
|
|
}
|
||
|
|
|
||
|
|
vMask, xMask, bitsPerPixel := uint32(0), int32(0), uint32(8>>t.bits)
|
||
|
|
switch t.bits {
|
||
|
|
case 1:
|
||
|
|
vMask, xMask = 0x0f, 0x01
|
||
|
|
case 2:
|
||
|
|
vMask, xMask = 0x03, 0x03
|
||
|
|
case 3:
|
||
|
|
vMask, xMask = 0x01, 0x07
|
||
|
|
}
|
||
|
|
|
||
|
|
d, p, v, dst := 0, 0, uint32(0), make([]byte, 4*t.oldWidth*h)
|
||
|
|
for y := int32(0); y < h; y++ {
|
||
|
|
for x := int32(0); x < t.oldWidth; x++ {
|
||
|
|
if x&xMask == 0 {
|
||
|
|
v = uint32(pix[p+1])
|
||
|
|
p += 4
|
||
|
|
}
|
||
|
|
|
||
|
|
i := 4 * (v & vMask)
|
||
|
|
dst[d+0] = t.pix[i+0]
|
||
|
|
dst[d+1] = t.pix[i+1]
|
||
|
|
dst[d+2] = t.pix[i+2]
|
||
|
|
dst[d+3] = t.pix[i+3]
|
||
|
|
d += 4
|
||
|
|
|
||
|
|
v >>= bitsPerPixel
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return dst
|
||
|
|
}
|
||
|
|
|
||
|
|
func abs(x int32) int32 {
|
||
|
|
if x < 0 {
|
||
|
|
return -x
|
||
|
|
}
|
||
|
|
return x
|
||
|
|
}
|
||
|
|
|
||
|
|
func avg2(a, b uint8) uint8 {
|
||
|
|
return uint8((int32(a) + int32(b)) / 2)
|
||
|
|
}
|
||
|
|
|
||
|
|
func clampAddSubtractFull(a, b, c uint8) uint8 {
|
||
|
|
x := int32(a) + int32(b) - int32(c)
|
||
|
|
if x < 0 {
|
||
|
|
return 0
|
||
|
|
}
|
||
|
|
if x > 255 {
|
||
|
|
return 255
|
||
|
|
}
|
||
|
|
return uint8(x)
|
||
|
|
}
|
||
|
|
|
||
|
|
func clampAddSubtractHalf(a, b uint8) uint8 {
|
||
|
|
x := int32(a) + (int32(a)-int32(b))/2
|
||
|
|
if x < 0 {
|
||
|
|
return 0
|
||
|
|
}
|
||
|
|
if x > 255 {
|
||
|
|
return 255
|
||
|
|
}
|
||
|
|
return uint8(x)
|
||
|
|
}
|