diff --git a/src/pkg/image/decode_test.go b/src/pkg/image/decode_test.go index 46bdd9ab8f..e03b12deed 100644 --- a/src/pkg/image/decode_test.go +++ b/src/pkg/image/decode_test.go @@ -44,6 +44,15 @@ func decode(filename string) (image.Image, string, os.Error) { return image.Decode(bufio.NewReader(f)) } +func decodeConfig(filename string) (image.Config, string, os.Error) { + f, err := os.Open(filename) + if err != nil { + return image.Config{}, "", err + } + defer f.Close() + return image.DecodeConfig(bufio.NewReader(f)) +} + func delta(u0, u1 uint32) int { d := int(u0) - int(u1) if d < 0 { @@ -69,7 +78,7 @@ func TestDecode(t *testing.T) { } loop: for _, it := range imageTests { - m, _, err := decode(it.filename) + m, imageFormat, err := decode(it.filename) if err != nil { t.Errorf("%s: %v", it.filename, err) continue loop @@ -87,5 +96,16 @@ loop: } } } + if imageFormat == "gif" { + // Each frame of a GIF can have a frame-local palette override the + // GIF-global palette. Thus, image.Decode can yield a different ColorModel + // than image.DecodeConfig. + continue + } + c, _, err := decodeConfig(it.filename) + if m.ColorModel() != c.ColorModel { + t.Errorf("%s: color models differ", it.filename) + continue loop + } } } diff --git a/src/pkg/image/jpeg/reader.go b/src/pkg/image/jpeg/reader.go index 74df9ac4b7..f3a473b351 100644 --- a/src/pkg/image/jpeg/reader.go +++ b/src/pkg/image/jpeg/reader.go @@ -41,16 +41,22 @@ type block [blockSize]int const ( blockSize = 64 // A DCT block is 8x8. - dcTableClass = 0 - acTableClass = 1 - maxTc = 1 - maxTh = 3 - maxTq = 3 + dcTable = 0 + acTable = 1 + maxTc = 1 + maxTh = 3 + maxTq = 3 - // We only support 4:4:4, 4:2:2 and 4:2:0 downsampling, and assume that the components are Y, Cb, Cr. - nComponent = 3 - maxH = 2 - maxV = 2 + // A grayscale JPEG image has only a Y component. + nGrayComponent = 1 + // A color JPEG image has Y, Cb and Cr components. + nColorComponent = 3 + + // We only support 4:4:4, 4:2:2 and 4:2:0 downsampling, and therefore the + // number of luma samples per chroma sample is at most 2 in the horizontal + // and 2 in the vertical direction. + maxH = 2 + maxV = 2 ) const ( @@ -90,9 +96,11 @@ type Reader interface { type decoder struct { r Reader width, height int - img *ycbcr.YCbCr + img1 *image.Gray + img3 *ycbcr.YCbCr ri int // Restart Interval. - comps [nComponent]component + nComp int + comp [nColorComponent]component huff [maxTc + 1][maxTh + 1]huffman quant [maxTq + 1]block b bits @@ -117,10 +125,15 @@ func (d *decoder) ignore(n int) os.Error { // Specified in section B.2.2. func (d *decoder) processSOF(n int) os.Error { - if n != 6+3*nComponent { + switch n { + case 6 + 3*nGrayComponent: + d.nComp = nGrayComponent + case 6 + 3*nColorComponent: + d.nComp = nColorComponent + default: return UnsupportedError("SOF has wrong length") } - _, err := io.ReadFull(d.r, d.tmp[0:6+3*nComponent]) + _, err := io.ReadFull(d.r, d.tmp[:n]) if err != nil { return err } @@ -130,26 +143,28 @@ func (d *decoder) processSOF(n int) os.Error { } d.height = int(d.tmp[1])<<8 + int(d.tmp[2]) d.width = int(d.tmp[3])<<8 + int(d.tmp[4]) - if d.tmp[5] != nComponent { + if int(d.tmp[5]) != d.nComp { return UnsupportedError("SOF has wrong number of image components") } - for i := 0; i < nComponent; i++ { + for i := 0; i < d.nComp; i++ { hv := d.tmp[7+3*i] - d.comps[i].h = int(hv >> 4) - d.comps[i].v = int(hv & 0x0f) - d.comps[i].c = d.tmp[6+3*i] - d.comps[i].tq = d.tmp[8+3*i] - // We only support YCbCr images, and 4:4:4, 4:2:2 or 4:2:0 chroma downsampling ratios. This implies that - // the (h, v) values for the Y component are either (1, 1), (2, 1) or (2, 2), and the - // (h, v) values for the Cr and Cb components must be (1, 1). + d.comp[i].h = int(hv >> 4) + d.comp[i].v = int(hv & 0x0f) + d.comp[i].c = d.tmp[6+3*i] + d.comp[i].tq = d.tmp[8+3*i] + if d.nComp == nGrayComponent { + continue + } + // For color images, we only support 4:4:4, 4:2:2 or 4:2:0 chroma + // downsampling ratios. This implies that the (h, v) values for the Y + // component are either (1, 1), (2, 1) or (2, 2), and the (h, v) + // values for the Cr and Cb components must be (1, 1). if i == 0 { if hv != 0x11 && hv != 0x21 && hv != 0x22 { return UnsupportedError("luma downsample ratio") } - } else { - if hv != 0x11 { - return UnsupportedError("chroma downsample ratio") - } + } else if hv != 0x11 { + return UnsupportedError("chroma downsample ratio") } } return nil @@ -181,75 +196,87 @@ func (d *decoder) processDQT(n int) os.Error { return nil } +// makeImg allocates and initializes the destination image. +func (d *decoder) makeImg(h0, v0, mxx, myy int) { + if d.nComp == nGrayComponent { + d.img1 = image.NewGray(8*mxx, 8*myy) + return + } + var subsampleRatio ycbcr.SubsampleRatio + n := h0 * v0 + switch n { + case 1: + subsampleRatio = ycbcr.SubsampleRatio444 + case 2: + subsampleRatio = ycbcr.SubsampleRatio422 + case 4: + subsampleRatio = ycbcr.SubsampleRatio420 + default: + panic("unreachable") + } + b := make([]byte, mxx*myy*(1*8*8*n+2*8*8)) + d.img3 = &ycbcr.YCbCr{ + Y: b[mxx*myy*(0*8*8*n+0*8*8) : mxx*myy*(1*8*8*n+0*8*8)], + Cb: b[mxx*myy*(1*8*8*n+0*8*8) : mxx*myy*(1*8*8*n+1*8*8)], + Cr: b[mxx*myy*(1*8*8*n+1*8*8) : mxx*myy*(1*8*8*n+2*8*8)], + SubsampleRatio: subsampleRatio, + YStride: mxx * 8 * h0, + CStride: mxx * 8, + Rect: image.Rect(0, 0, d.width, d.height), + } +} + // Specified in section B.2.3. func (d *decoder) processSOS(n int) os.Error { - if n != 4+2*nComponent { + if d.nComp == 0 { + return FormatError("missing SOF marker") + } + if n != 4+2*d.nComp { return UnsupportedError("SOS has wrong length") } - _, err := io.ReadFull(d.r, d.tmp[0:4+2*nComponent]) + _, err := io.ReadFull(d.r, d.tmp[0:4+2*d.nComp]) if err != nil { return err } - if d.tmp[0] != nComponent { + if int(d.tmp[0]) != d.nComp { return UnsupportedError("SOS has wrong number of image components") } - var scanComps [nComponent]struct { + var scan [nColorComponent]struct { td uint8 // DC table selector. ta uint8 // AC table selector. } - for i := 0; i < nComponent; i++ { + for i := 0; i < d.nComp; i++ { cs := d.tmp[1+2*i] // Component selector. - if cs != d.comps[i].c { + if cs != d.comp[i].c { return UnsupportedError("scan components out of order") } - scanComps[i].td = d.tmp[2+2*i] >> 4 - scanComps[i].ta = d.tmp[2+2*i] & 0x0f + scan[i].td = d.tmp[2+2*i] >> 4 + scan[i].ta = d.tmp[2+2*i] & 0x0f } // mxx and myy are the number of MCUs (Minimum Coded Units) in the image. - h0, v0 := d.comps[0].h, d.comps[0].v // The h and v values from the Y components. + h0, v0 := d.comp[0].h, d.comp[0].v // The h and v values from the Y components. mxx := (d.width + 8*h0 - 1) / (8 * h0) myy := (d.height + 8*v0 - 1) / (8 * v0) - if d.img == nil { - var subsampleRatio ycbcr.SubsampleRatio - n := h0 * v0 - switch n { - case 1: - subsampleRatio = ycbcr.SubsampleRatio444 - case 2: - subsampleRatio = ycbcr.SubsampleRatio422 - case 4: - subsampleRatio = ycbcr.SubsampleRatio420 - default: - panic("unreachable") - } - b := make([]byte, mxx*myy*(1*8*8*n+2*8*8)) - d.img = &ycbcr.YCbCr{ - Y: b[mxx*myy*(0*8*8*n+0*8*8) : mxx*myy*(1*8*8*n+0*8*8)], - Cb: b[mxx*myy*(1*8*8*n+0*8*8) : mxx*myy*(1*8*8*n+1*8*8)], - Cr: b[mxx*myy*(1*8*8*n+1*8*8) : mxx*myy*(1*8*8*n+2*8*8)], - SubsampleRatio: subsampleRatio, - YStride: mxx * 8 * h0, - CStride: mxx * 8, - Rect: image.Rect(0, 0, d.width, d.height), - } + if d.img1 == nil && d.img3 == nil { + d.makeImg(h0, v0, mxx, myy) } mcu, expectedRST := 0, uint8(rst0Marker) var ( - allZeroes, b block - dc [nComponent]int + b block + dc [nColorComponent]int ) for my := 0; my < myy; my++ { for mx := 0; mx < mxx; mx++ { - for i := 0; i < nComponent; i++ { - qt := &d.quant[d.comps[i].tq] - for j := 0; j < d.comps[i].h*d.comps[i].v; j++ { + for i := 0; i < d.nComp; i++ { + qt := &d.quant[d.comp[i].tq] + for j := 0; j < d.comp[i].h*d.comp[i].v; j++ { // TODO(nigeltao): make this a "var b block" once the compiler's escape // analysis is good enough to allocate it on the stack, not the heap. - b = allZeroes + b = block{} // Decode the DC coefficient, as specified in section F.2.2.1. - value, err := d.decodeHuffman(&d.huff[dcTableClass][scanComps[i].td]) + value, err := d.decodeHuffman(&d.huff[dcTable][scan[i].td]) if err != nil { return err } @@ -265,7 +292,7 @@ func (d *decoder) processSOS(n int) os.Error { // Decode the AC coefficients, as specified in section F.2.2.2. for k := 1; k < blockSize; k++ { - value, err := d.decodeHuffman(&d.huff[acTableClass][scanComps[i].ta]) + value, err := d.decodeHuffman(&d.huff[acTable][scan[i].ta]) if err != nil { return err } @@ -290,15 +317,28 @@ func (d *decoder) processSOS(n int) os.Error { } // Perform the inverse DCT and store the MCU component to the image. - switch i { - case 0: - mx0 := h0*mx + (j % 2) - my0 := v0*my + (j / 2) - idct(d.img.Y[8*(my0*d.img.YStride+mx0):], d.img.YStride, &b) - case 1: - idct(d.img.Cb[8*(my*d.img.CStride+mx):], d.img.CStride, &b) - case 2: - idct(d.img.Cr[8*(my*d.img.CStride+mx):], d.img.CStride, &b) + if d.nComp == nGrayComponent { + idct(d.tmp[:64], 8, &b) + // Convert from []uint8 to []image.GrayColor. + p := d.img1.Pix[8*(my*d.img1.Stride+mx):] + for y := 0; y < 8; y++ { + dst := p[y*d.img1.Stride:] + src := d.tmp[8*y:] + for x := 0; x < 8; x++ { + dst[x] = image.GrayColor{src[x]} + } + } + } else { + switch i { + case 0: + mx0 := h0*mx + (j % 2) + my0 := v0*my + (j / 2) + idct(d.img3.Y[8*(my0*d.img3.YStride+mx0):], d.img3.YStride, &b) + case 1: + idct(d.img3.Cb[8*(my*d.img3.CStride+mx):], d.img3.CStride, &b) + case 2: + idct(d.img3.Cr[8*(my*d.img3.CStride+mx):], d.img3.CStride, &b) + } } } // for j } // for i @@ -320,9 +360,7 @@ func (d *decoder) processSOS(n int) os.Error { // Reset the Huffman decoder. d.b = bits{} // Reset the DC components, as per section F.2.1.3.1. - for i := 0; i < nComponent; i++ { - dc[i] = 0 - } + dc = [nColorComponent]int{} } } // for mx } // for my @@ -410,7 +448,13 @@ func (d *decoder) decode(r io.Reader, configOnly bool) (image.Image, os.Error) { return nil, err } } - return d.img, nil + if d.img1 != nil { + return d.img1, nil + } + if d.img3 != nil { + return d.img3, nil + } + return nil, FormatError("missing SOS marker") } // Decode reads a JPEG image from r and returns it as an image.Image. @@ -426,7 +470,13 @@ func DecodeConfig(r io.Reader) (image.Config, os.Error) { if _, err := d.decode(r, true); err != nil { return image.Config{}, err } - return image.Config{image.RGBAColorModel, d.width, d.height}, nil + switch d.nComp { + case nGrayComponent: + return image.Config{image.GrayColorModel, d.width, d.height}, nil + case nColorComponent: + return image.Config{ycbcr.YCbCrColorModel, d.width, d.height}, nil + } + return image.Config{}, FormatError("missing SOF marker") } func init() { diff --git a/src/pkg/image/jpeg/writer.go b/src/pkg/image/jpeg/writer.go index 52b3dc4e2c..4a861b3951 100644 --- a/src/pkg/image/jpeg/writer.go +++ b/src/pkg/image/jpeg/writer.go @@ -315,21 +315,21 @@ func (e *encoder) writeDQT() { // writeSOF0 writes the Start Of Frame (Baseline) marker. func (e *encoder) writeSOF0(size image.Point) { - markerlen := 8 + 3*nComponent + markerlen := 8 + 3*nColorComponent e.writeMarkerHeader(sof0Marker, markerlen) e.buf[0] = 8 // 8-bit color. e.buf[1] = uint8(size.Y >> 8) e.buf[2] = uint8(size.Y & 0xff) e.buf[3] = uint8(size.X >> 8) e.buf[4] = uint8(size.X & 0xff) - e.buf[5] = nComponent - for i := 0; i < nComponent; i++ { + e.buf[5] = nColorComponent + for i := 0; i < nColorComponent; i++ { e.buf[3*i+6] = uint8(i + 1) // We use 4:2:0 chroma subsampling. e.buf[3*i+7] = "\x22\x11\x11"[i] e.buf[3*i+8] = "\x00\x01\x01"[i] } - e.write(e.buf[:3*(nComponent-1)+9]) + e.write(e.buf[:3*(nColorComponent-1)+9]) } // writeDHT writes the Define Huffman Table marker.