136 lines
3.8 KiB
Go
136 lines
3.8 KiB
Go
package goimagehash
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import (
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"image"
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)
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type WebPUpsampleLinePairFunc func(topY []uint8, bottomY []uint8,
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topU []uint8, topV []uint8,
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bottomU []uint8, bottomV []uint8,
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topDst []uint8, bottomDst []uint8, len int)
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func FancyUpscale(yuv *image.YCbCr) *image.RGBA {
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rgb := image.NewRGBA(image.Rect(0, 0, yuv.Rect.Dx(), yuv.Rect.Dy()))
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var (
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upsample WebPUpsampleLinePairFunc = UpsampleRgbaLinePair
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lastRow = yuv.Rect.Dy()
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mbW = yuv.Rect.Dx()
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)
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// First line is special cased. We mirror the u/v samples at boundary.
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upsample(yuv.Y[:yuv.YStride], nil,
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yuv.Cb[:yuv.CStride], yuv.Cr[:yuv.CStride],
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yuv.Cb[:yuv.CStride], yuv.Cr[:yuv.CStride],
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rgb.Pix[:rgb.Stride], nil,
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mbW,
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)
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var (
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topC int
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bottomC int
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topY int
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bottomY int
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topDst int
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bottomDst int
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)
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// Loop over each output pairs of row.
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for row := 1; row+1 < lastRow; row += 2 {
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topC = yuv.COffset(0, row)
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bottomC = topC + yuv.CStride
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topY = yuv.YOffset(0, row)
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bottomY = topY + yuv.YStride
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topDst = rgb.PixOffset(0, row)
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bottomDst = topDst + rgb.Stride
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upsample(yuv.Y[topY:bottomY], yuv.Y[bottomY:bottomY+yuv.YStride],
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yuv.Cb[topC:bottomC], yuv.Cr[topC:bottomC],
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yuv.Cb[bottomC:bottomC+yuv.CStride], yuv.Cr[bottomC:bottomC+yuv.CStride],
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rgb.Pix[topDst:bottomDst], rgb.Pix[bottomDst:bottomDst+rgb.Stride],
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mbW,
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)
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}
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// Process the very last row of even-sized picture
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if lastRow%2 == 0 {
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upsample(yuv.Y[len(yuv.Y)-yuv.YStride:], nil,
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yuv.Cb[len(yuv.Cb)-yuv.CStride:], yuv.Cr[len(yuv.Cr)-yuv.CStride:],
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yuv.Cb[len(yuv.Cb)-yuv.CStride:], yuv.Cr[len(yuv.Cr)-yuv.CStride:],
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rgb.Pix[len(rgb.Pix)-rgb.Stride:], nil,
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mbW,
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)
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}
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return rgb
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}
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func UpsampleRgbaLinePair(topY []uint8, bottomY []uint8,
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topU []uint8, topV []uint8,
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bottomU []uint8, bottomV []uint8,
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topDst []uint8, bottomDst []uint8, rowLength int,
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) {
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var (
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x int
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lastPixelPair = (rowLength - 1) >> 1
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tlUV = (uint32(topU[0]) | (uint32(topV[0]) << 16)) /* top-left sample */
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lUV = (uint32(bottomU[0]) | (uint32(bottomV[0]) << 16)) /* left-sample */
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)
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{
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uv0 := (3*tlUV + lUV + 0x00020002) >> 2
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dst := VP8YuvToRgba(topY[0], uint8(uv0&0xff), uint8((uv0 >> 16)))
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copy(topDst[0:], dst[:])
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}
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if bottomY != nil {
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uv0 := (3*lUV + tlUV + 0x00020002) >> 2
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dst := VP8YuvToRgba(bottomY[0], uint8(uv0&0xff), uint8(uv0>>16))
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copy(bottomDst[0:], dst[:])
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}
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for x = 1; x <= lastPixelPair; x++ {
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var (
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tUV = (uint32(topU[x]) | (uint32(topV[x]) << 16)) /* top sample */
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uv = (uint32(bottomU[x]) | (uint32(bottomV[x]) << 16)) /* sample */
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/* precompute invariant values associated with first and second diagonals*/
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avg = tlUV + tUV + lUV + uv + 0x00080008
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diag12 = (avg + 2*(tUV+lUV)) >> 3
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diag03 = (avg + 2*(tlUV+uv)) >> 3
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)
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{
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var (
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uv0 = (diag12 + tlUV) >> 1
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uv1 = (diag03 + tUV) >> 1
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)
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dst := VP8YuvToRgba(topY[2*x-1], uint8(uv0&0xff), uint8(uv0>>16))
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copy(topDst[(2*x-1)*4:], dst[:])
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dst = VP8YuvToRgba(topY[2*x-0], uint8(uv1&0xff), uint8(uv1>>16))
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copy(topDst[(2*x-0)*4:], dst[:])
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}
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if bottomY != nil {
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var (
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uv0 = (diag03 + lUV) >> 1
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uv1 = (diag12 + uv) >> 1
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)
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dst := VP8YuvToRgba(bottomY[2*x-1], uint8(uv0&0xff), uint8(uv0>>16))
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copy(bottomDst[(2*x-1)*4:], dst[:])
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dst = VP8YuvToRgba(bottomY[2*x+0], uint8(uv1&0xff), uint8(uv1>>16))
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copy(bottomDst[(2*x+0)*4:], dst[:])
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}
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tlUV = tUV
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lUV = uv
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}
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if rowLength%2 == 0 {
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{
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uv0 := (3*tlUV + lUV + 0x00020002) >> 2
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dst := VP8YuvToRgba(topY[rowLength-1], uint8(uv0&0xff), uint8(uv0>>16))
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copy(topDst[(rowLength-1)*4:], dst[:])
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}
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if bottomY != nil {
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uv0 := (3*lUV + tlUV + 0x00020002) >> 2
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dst := VP8YuvToRgba(bottomY[rowLength-1], uint8(uv0&0xff), uint8(uv0>>16))
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copy(bottomDst[(rowLength-1)*4:], dst[:])
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}
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}
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}
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