136 lines
4.0 KiB
Go
136 lines
4.0 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(top_y []uint8, bottom_y []uint8,
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top_u []uint8, top_v []uint8,
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bottom_u []uint8, bottom_v []uint8,
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top_dst []uint8, bottom_dst []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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last_row int = yuv.Rect.Dy()
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mb_w int = 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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mb_w,
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)
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var (
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top_c int
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bottom_c int
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top_y int
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bottom_y int
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top_dst int
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bottom_dst 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 < last_row; row += 2 {
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top_c = yuv.COffset(0, row)
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bottom_c = top_c + yuv.CStride
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top_y = yuv.YOffset(0, row)
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bottom_y = top_y + yuv.YStride
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top_dst = rgb.PixOffset(0, row)
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bottom_dst = top_dst + rgb.Stride
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upsample(yuv.Y[top_y:bottom_y], yuv.Y[bottom_y:bottom_y+yuv.YStride],
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yuv.Cb[top_c:bottom_c], yuv.Cr[top_c:bottom_c],
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yuv.Cb[bottom_c:bottom_c+yuv.CStride], yuv.Cr[bottom_c:bottom_c+yuv.CStride],
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rgb.Pix[top_dst:bottom_dst], rgb.Pix[bottom_dst:bottom_dst+rgb.Stride],
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mb_w,
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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 last_row%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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mb_w,
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)
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}
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return rgb
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}
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func UpsampleRgbaLinePair(top_y []uint8, bottom_y []uint8,
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top_u []uint8, top_v []uint8,
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bottom_u []uint8, bottom_v []uint8,
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top_dst []uint8, bottom_dst []uint8, rowLength int,
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) {
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var (
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x int
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last_pixel_pair int = (rowLength - 1) >> 1
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tl_uv uint32 = (uint32(top_u[0]) | (uint32(top_v[0]) << 16)) /* top-left sample */
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l_uv uint32 = (uint32(bottom_u[0]) | (uint32(bottom_v[0]) << 16)) /* left-sample */
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)
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{
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var uv0 uint32 = (3*tl_uv + l_uv + 0x00020002) >> 2
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dst := VP8YuvToRgba(top_y[0], uint8(uv0&0xff), uint8((uv0 >> 16)))
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copy(top_dst[0:], dst[:])
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}
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if bottom_y != nil {
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var uv0 uint32 = (3*l_uv + tl_uv + 0x00020002) >> 2
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dst := VP8YuvToRgba(bottom_y[0], uint8(uv0&0xff), uint8(uv0>>16))
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copy(bottom_dst[0:], dst[:])
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}
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for x = 1; x <= last_pixel_pair; x++ {
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var (
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t_uv uint32 = (uint32(top_u[x]) | (uint32(top_v[x]) << 16)) /* top sample */
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uv uint32 = (uint32(bottom_u[x]) | (uint32(bottom_v[x]) << 16)) /* sample */
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/* precompute invariant values associated with first and second diagonals*/
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avg uint32 = tl_uv + t_uv + l_uv + uv + 0x00080008
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diag_12 uint32 = (avg + 2*(t_uv+l_uv)) >> 3
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diag_03 uint32 = (avg + 2*(tl_uv+uv)) >> 3
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)
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{
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var (
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uv0 uint32 = (diag_12 + tl_uv) >> 1
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uv1 uint32 = (diag_03 + t_uv) >> 1
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)
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dst := VP8YuvToRgba(top_y[2*x-1], uint8(uv0&0xff), uint8(uv0>>16))
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copy(top_dst[(2*x-1)*4:], dst[:])
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dst = VP8YuvToRgba(top_y[2*x-0], uint8(uv1&0xff), uint8(uv1>>16))
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copy(top_dst[(2*x-0)*4:], dst[:])
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}
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if bottom_y != nil {
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var (
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uv0 uint32 = (diag_03 + l_uv) >> 1
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uv1 uint32 = (diag_12 + uv) >> 1
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)
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dst := VP8YuvToRgba(bottom_y[2*x-1], uint8(uv0&0xff), uint8(uv0>>16))
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copy(bottom_dst[(2*x-1)*4:], dst[:])
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dst = VP8YuvToRgba(bottom_y[2*x+0], uint8(uv1&0xff), uint8(uv1>>16))
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copy(bottom_dst[(2*x+0)*4:], dst[:])
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}
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tl_uv = t_uv
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l_uv = uv
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}
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if rowLength%2 == 0 {
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{
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var uv0 uint32 = (3*tl_uv + l_uv + 0x00020002) >> 2
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dst := VP8YuvToRgba(top_y[rowLength-1], uint8(uv0&0xff), uint8(uv0>>16))
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copy(top_dst[(rowLength-1)*4:], dst[:])
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}
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if bottom_y != nil {
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var uv0 uint32 = (3*l_uv + tl_uv + 0x00020002) >> 2
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dst := VP8YuvToRgba(bottom_y[rowLength-1], uint8(uv0&0xff), uint8(uv0>>16))
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copy(bottom_dst[(rowLength-1)*4:], dst[:])
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}
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}
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}
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