constrast enhancement for browser image

pkg/config/config.go

@@ -8,6 +8,7 @@ import (
 type Config struct {
 	CoRegistration CoRegistrationConfig `yaml:"coregistration" mapstructure:"coregistration"`
 	Radiation      RadiationConfig      `yaml:"radiation" mapstructure:"radiation"`
+	BrowserImg     BrowserImgConfig     `yaml:"browser_img" mapstructure:"browser_img"`
 	LogLevel       logrus.Level         `yaml:"log_level" mapstructure:"log_level"`
 }
 
@@ -33,6 +34,12 @@ type RadiationConfig struct {
 	HFBandStopWidth     int     `yaml:"hf_band_stop_width" mapstructure:"hf_band_stop_width"`
 }
 
+type BrowserImgConfig struct {
+	Enhancement        string  `yaml:"enhancement" mapstructure:"enhancement"`
+	CumulativeCutLower float64 `yaml:"cumulative_cut_lower" mapstructure:"cumulative_cut_lower"`
+	CumulativeCutUpper float64 `yaml:"cumulative_cut_upper" mapstructure:"cumulative_cut_upper"`
+}
+
 var GCONFIG Config
 
 func init() {
@@ -58,5 +65,10 @@ func init() {
 			HfRadiusRatio:       0.49,
 			HFBandStopWidth:     24,
 		},
+		BrowserImg: BrowserImgConfig{
+			Enhancement:        "StretchToCumulativeCutMinMax",
+			CumulativeCutLower: 0.01,
+			CumulativeCutUpper: 0.99,
+		},
 	}
 }

pkg/producer/enhancement.go

@@ -0,0 +1,124 @@
+package producer
+
+import (
+	"gocv.io/x/gocv"
+)
+
+const (
+	NoEnhancement                = "NoEnhancement"
+	StretchToMinimumMaximum      = "StretchToMinimumMaximum"
+	StretchToCumulativeCutMinMax = "StretchToCumulativeCutMinMax"
+)
+
+type ContrastEnhancement struct {
+	minimumValue         int
+	maximumValue         int
+	lookupTableOffset    int
+	lookupTable          []int
+	mRasterDataTypeRange int
+	enhancementType      string
+	//!< Range is [ min + cumulativeCutLower() * (max - min), min + cumulativeCutUpper() * (max - min) ]
+	cumulativeCutLower float64
+	cumulativeCutUpper float64
+}
+
+func NewContrastEnhancement(minimumValue, maximumValue int) *ContrastEnhancement {
+	ce := &ContrastEnhancement{
+		enhancementType:    StretchToMinimumMaximum,
+		cumulativeCutLower: 0,
+		cumulativeCutUpper: 1,
+	}
+	ce.minimumValue = minimumValue + int(ce.cumulativeCutLower)*(maximumValue-minimumValue)
+	ce.maximumValue = minimumValue + int(ce.cumulativeCutUpper)*(maximumValue-minimumValue)
+	ce.mRasterDataTypeRange = ce.maximumValue - ce.minimumValue
+	ce.lookupTableOffset = -1 * ce.minimumValue
+	ce.lookupTable = make([]int, ce.mRasterDataTypeRange+1)
+	ce.generateLookupTable()
+
+	return ce
+}
+
+func (ce ContrastEnhancement) enhance(value int) int {
+	if ce.enhancementType != NoEnhancement {
+		shiftedValue := value + ce.lookupTableOffset
+		if shiftedValue >= 0 && shiftedValue < ce.mRasterDataTypeRange+1 {
+			return ce.lookupTable[shiftedValue]
+		}
+		return 0
+	}
+
+	return ce.linearMinMaxEnhancement(value)
+}
+
+func (ce *ContrastEnhancement) generateLookupTable() {
+	for i := range ce.lookupTable {
+		ce.lookupTable[i] = ce.linearMinMaxEnhancement(i - ce.lookupTableOffset)
+	}
+}
+
+func (ce ContrastEnhancement) linearMinMaxEnhancement(value int) int {
+	stretchedValue := (float64(value-ce.minimumValue) / float64(ce.mRasterDataTypeRange)) * 255.0
+	if stretchedValue < 0 {
+		return 0
+	} else if stretchedValue > 255 {
+		return 255
+	}
+	return int(stretchedValue)
+}
+
+func cumulativeCountCutEnhancement(img gocv.Mat, cumulativeCutLower, cumulativeCutUpper float64) gocv.Mat {
+	dataTypeMax := 65536
+	// 计算直方图
+	hist := make([]int, dataTypeMax)
+	for y := 0; y < img.Rows(); y++ {
+		for x := 0; x < img.Cols(); x++ {
+			hist[uint16(img.GetShortAt(y, x))]++
+		}
+	}
+
+	// 计算累积直方图
+	cdf := make([]int, dataTypeMax)
+	cdf[0] = hist[0]
+	for i := 1; i < dataTypeMax; i++ {
+		cdf[i] = cdf[i-1] + hist[i]
+	}
+
+	// 计算低高阈值
+	totalPixels := img.Rows() * img.Cols()
+	lowCutoff := int(float64(totalPixels) * cumulativeCutLower)
+	highCutoff := int(float64(totalPixels) * cumulativeCutUpper)
+
+	var lowerBound, upperBound int
+	for i, v := range cdf {
+		if v > lowCutoff {
+			lowerBound = i
+			break
+		}
+	}
+	for i := dataTypeMax - 1; i >= 0; i-- {
+		if cdf[i] < highCutoff {
+			upperBound = i
+			break
+		}
+	}
+
+	// 重新映射灰度值
+	enhancedImg := gocv.NewMatWithSize(img.Rows(), img.Cols(), gocv.MatTypeCV8U)
+	for y := 0; y < img.Rows(); y++ {
+		for x := 0; x < img.Cols(); x++ {
+			oldVal := uint16(img.GetShortAt(y, x))
+			newVal := (int(oldVal) - lowerBound) * 255 / (upperBound - lowerBound)
+			if newVal > 255 {
+				newVal = 255
+			}
+			if newVal < 0 {
+				newVal = 0
+			}
+
+			enhancedImg.SetUCharAt(y, x, uint8(newVal))
+		}
+	}
+
+	return enhancedImg
+
+}

pkg/producer/jpg.go

@@ -8,6 +8,7 @@ import (
 	"github.com/airbusgeo/godal"
 	log "github.com/sirupsen/logrus"
 	"gocv.io/x/gocv"
+	"starwiz.cn/sjy01/image-proc/pkg/config"
 )
 
 func GTiffToJPG(ftiff, fjpg string, reversed bool) error {
@@ -58,12 +59,24 @@ func GTiffToJPG(ftiff, fjpg string, reversed bool) error {
 
 	channels := gocv.Split(img)
 	for i, ch := range channels {
-		// 2. 计算图像的最小值和最大值
+		switch config.GCONFIG.BrowserImg.Enhancement {
+		case NoEnhancement:
+		case StretchToMinimumMaximum:
 			minVal, maxVal, _, _ := gocv.MinMaxLoc(ch)
-		// 3. 将16位图像线性拉伸到8位图像
-		scale := 255.0 / (maxVal - minVal)
-		shift := -minVal * scale
-		ch.ConvertToWithParams(&channels[i], gocv.MatTypeCV8U, scale, shift)
+			ce := NewContrastEnhancement(int(minVal), int(maxVal))
+			for y := 0; y < height; y++ {
+				for x := 0; x < width; x++ {
+					value := int(uint16(ch.GetShortAt(y, x)))
+					value = ce.enhance(value)
+					ch.SetShortAt(y, x, int16(value))
+				}
+			}
+		case StretchToCumulativeCutMinMax:
+			channels[i] = cumulativeCountCutEnhancement(ch,
+				config.GCONFIG.BrowserImg.CumulativeCutLower,
+				config.GCONFIG.BrowserImg.CumulativeCutUpper)
+			ch.Close()
+		}
 	}
 
 	img8bit := gocv.NewMat()
@@ -82,14 +95,16 @@ func GTiffToJPG(ftiff, fjpg string, reversed bool) error {
 		image.Point{X: img8bit.Cols() / 2, Y: img8bit.Rows() / 2},
 		0, 0, gocv.InterpolationCubic)
 
+	gocv.IMWrite(fjpg, img8bit)
+
 	// 7. 应用伽玛校正提升亮度
-	gammaCorrected := applyGammaCorrection(img8bit, 1.6) // 伽玛值
-	defer gammaCorrected.Close()
-	ok := gocv.IMWriteWithParams(fjpg, gammaCorrected, []int{gocv.IMWriteJpegOptimize, 1})
-	if !ok {
-		err = fmt.Errorf("error saving %s", fjpg)
-		return err
-	}
+	// gammaCorrected := applyGammaCorrection(img8bit, 1.6) // 伽玛值
+	// defer gammaCorrected.Close()
+	// ok := gocv.IMWriteWithParams(fjpg, gammaCorrected, []int{gocv.IMWriteJpegOptimize, 1})
+	// if !ok {
+	// 	err = fmt.Errorf("error saving %s", fjpg)
+	// 	return err
+	// }
 	return nil
 }