Ted Unangst
5 years ago
parent
d121408464
commit
af849f4371
@ -1,148 +0,0 @@
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//
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// Copyright (c) 2019 Ted Unangst <tedu@tedunangst.com>
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//
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// Permission to use, copy, modify, and distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice appear in all copies.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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package main
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import (
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"bytes"
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"fmt"
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"image"
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"image/jpeg"
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"image/png"
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"math"
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)
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func lineate(s uint8) float64 {
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x := float64(s)
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x /= 255.0
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if x < 0.04045 {
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x /= 12.92
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} else {
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x += 0.055
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x /= 1.055
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x = math.Pow(x, 2.4)
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}
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return x
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}
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func delineate(x float64) uint8 {
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if x > 0.0031308 {
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x = math.Pow(x, 1/2.4)
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x *= 1.055
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x -= 0.055
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} else {
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x *= 12.92
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}
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x *= 255.0
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return uint8(x)
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}
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func blend(d []byte, s1, s2, s3, s4 int) byte {
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l1 := lineate(d[s1])
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l2 := lineate(d[s2])
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l3 := lineate(d[s3])
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l4 := lineate(d[s4])
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return delineate((l1 + l2 + l3 + l4) / 4.0)
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}
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func squish(d []byte, s1, s2, s3, s4 int) byte {
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return uint8((uint32(d[s1]) + uint32(d[s2]) + uint32(d[s3]) + uint32(d[s4])) / 4)
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}
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func vacuumwrap(img image.Image, format string) ([]byte, string, error) {
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maxdimension := 2048
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for img.Bounds().Max.X > maxdimension || img.Bounds().Max.Y > maxdimension {
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switch oldimg := img.(type) {
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case *image.NRGBA:
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w, h := oldimg.Rect.Max.X/2, oldimg.Rect.Max.Y/2
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newimg := image.NewNRGBA(image.Rectangle{Max: image.Point{X: w, Y: h}})
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for j := 0; j < h; j++ {
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for i := 0; i < w; i++ {
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p := newimg.Stride*j + i*4
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q1 := oldimg.Stride*(j*2+0) + i*4*2
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q2 := oldimg.Stride*(j*2+1) + i*4*2
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newimg.Pix[p+0] = blend(oldimg.Pix, q1+0, q1+4, q2+0, q2+4)
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newimg.Pix[p+1] = blend(oldimg.Pix, q1+1, q1+5, q2+1, q2+5)
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newimg.Pix[p+2] = blend(oldimg.Pix, q1+2, q1+6, q2+2, q2+6)
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newimg.Pix[p+3] = squish(oldimg.Pix, q1+3, q1+7, q2+3, q2+7)
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}
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}
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img = newimg
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case *image.YCbCr:
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w, h := oldimg.Rect.Max.X/2, oldimg.Rect.Max.Y/2
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newimg := image.NewYCbCr(image.Rectangle{Max: image.Point{X: w, Y: h}},
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oldimg.SubsampleRatio)
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for j := 0; j < h; j++ {
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for i := 0; i < w; i++ {
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p := newimg.YStride*j + i
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q1 := oldimg.YStride*(j*2+0) + i*2
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q2 := oldimg.YStride*(j*2+1) + i*2
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newimg.Y[p+0] = blend(oldimg.Y, q1+0, q1+1, q2+0, q2+1)
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}
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}
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switch newimg.SubsampleRatio {
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case image.YCbCrSubsampleRatio444:
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w, h = w, h
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case image.YCbCrSubsampleRatio422:
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w, h = w/2, h
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case image.YCbCrSubsampleRatio420:
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w, h = w/2, h/2
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case image.YCbCrSubsampleRatio440:
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w, h = w, h/2
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case image.YCbCrSubsampleRatio411:
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w, h = w/4, h
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case image.YCbCrSubsampleRatio410:
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w, h = w/4, h/2
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}
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for j := 0; j < h; j++ {
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for i := 0; i < w; i++ {
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p := newimg.CStride*j + i
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q1 := oldimg.CStride*(j*2+0) + i*2
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q2 := oldimg.CStride*(j*2+1) + i*2
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newimg.Cb[p+0] = blend(oldimg.Cb, q1+0, q1+1, q2+0, q2+1)
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newimg.Cr[p+0] = blend(oldimg.Cr, q1+0, q1+1, q2+0, q2+1)
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}
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}
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img = newimg
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default:
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return nil, "", fmt.Errorf("can't support image format")
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}
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}
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maxsize := 512 * 1024
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quality := 80
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var buf bytes.Buffer
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for {
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switch format {
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case "png":
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png.Encode(&buf, img)
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case "jpeg":
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jpeg.Encode(&buf, img, &jpeg.Options{Quality: quality})
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default:
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return nil, "", fmt.Errorf("can't encode format: %s", format)
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}
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if buf.Len() > maxsize && quality > 30 {
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switch format {
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case "png":
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format = "jpeg"
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case "jpeg":
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quality -= 10
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}
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buf.Reset()
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continue
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}
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break
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}
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return buf.Bytes(), format, nil
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}
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