Introduce ColorMode enum

app/src/main/java/org/fairscan/app/data/ImageRepository.kt

@@ -33,6 +33,7 @@ import org.fairscan.app.domain.PageMetadata
 import org.fairscan.app.domain.PageViewKey
 import org.fairscan.app.domain.Rotation
 import org.fairscan.app.domain.ScanPage
+import org.fairscan.imageprocessing.ColorMode
 import org.fairscan.imageprocessing.Point
 import org.fairscan.imageprocessing.Quad
 import java.io.File
@@ -151,7 +152,7 @@ class ImageRepository(
                     quad = metadata.normalizedQuad.toSerializable(),
                     baseRotationDegrees = metadata.baseRotation.degrees,
                     manualRotationDegrees = Rotation.R0.degrees,
-                    isColored = metadata.isColored
+                    isColored = metadata.autoColorMode == ColorMode.COLOR
                 )
             )
             saveMetadata()
@@ -313,6 +314,6 @@ fun PageV2.toMetadata(): PageMetadata? {
     return PageMetadata(
         quad.toQuad(),
         Rotation.fromDegrees(baseRotationDegrees),
-        isColored
+        if (isColored) ColorMode.COLOR else ColorMode.GRAYSCALE
     )
 }

app/src/main/java/org/fairscan/app/domain/ExportPreparation.kt

@@ -98,7 +98,7 @@ private fun prepareJpegForHigh(
             decoded,
             quad,
             pageMetadata.baseRotation.add(manualRotation).degrees,
-            pageMetadata.isColored,
+            pageMetadata.autoColorMode,
             exportQuality.maxPixels
         )
         return Jpeg.fromMat(page, exportQuality.jpegQuality)

app/src/main/java/org/fairscan/app/domain/Page.kt

@@ -14,12 +14,13 @@
  */
 package org.fairscan.app.domain
 
+import org.fairscan.imageprocessing.ColorMode
 import org.fairscan.imageprocessing.Quad
 
 data class PageMetadata(
     val normalizedQuad: Quad,
     val baseRotation: Rotation,
-    val isColored: Boolean,
+    val autoColorMode: ColorMode,
 )
 
 data class ScanPage(

app/src/main/java/org/fairscan/app/ui/screens/camera/CameraScreen.kt

@@ -104,6 +104,7 @@ import org.fairscan.app.ui.components.pageCountText
 import org.fairscan.app.ui.dummyNavigation
 import org.fairscan.app.ui.fakeDocument
 import org.fairscan.app.ui.theme.FairScanTheme
+import org.fairscan.imageprocessing.ColorMode
 import org.fairscan.imageprocessing.Point
 import org.fairscan.imageprocessing.Quad
 
@@ -539,7 +540,7 @@ fun CameraScreenPreviewWithProcessedImage() {
         CapturedPage(
             debugImage("gallica.bnf.fr-bpt6k5530456s-1.jpg"),
             CompletableDeferred(Jpeg(ByteArray(0))),
-            PageMetadata(quad, R0, false))))
+            PageMetadata(quad, R0, ColorMode.COLOR))))
 }
 
 @Preview(showBackground = true, widthDp = 640, heightDp = 320)

app/src/main/java/org/fairscan/app/ui/screens/camera/CameraViewModel.kt

@@ -40,7 +40,7 @@ import org.fairscan.imageprocessing.Mask
 import org.fairscan.imageprocessing.Quad
 import org.fairscan.imageprocessing.detectDocumentQuad
 import org.fairscan.imageprocessing.extractDocument
-import org.fairscan.imageprocessing.isColoredDocument
+import org.fairscan.imageprocessing.autoColorMode
 import org.fairscan.imageprocessing.scaledTo
 import org.opencv.android.Utils
 import org.opencv.core.Mat
@@ -230,16 +230,16 @@ fun extractDocumentFromBitmap(
     val bgr = Mat()
     Imgproc.cvtColor(rgba, bgr, Imgproc.COLOR_RGBA2BGR) // CV_8UC4 → CV_8UC3
     rgba.release()
-    val isColored = isColoredDocument(bgr, mask, quad)
+    val colorMode = autoColorMode(bgr, mask, quad)
     val maxPixels = ExportQuality.BALANCED.maxPixels
-    val page = extractDocument(bgr, quad, rotationDegrees, isColored, maxPixels)
+    val page = extractDocument(bgr, quad, rotationDegrees, colorMode, maxPixels)
     val pageJpeg = Jpeg.fromMat(page, ExportQuality.BALANCED.jpegQuality)
     bgr.release()
     page.release()
 
     val normalizedQuad = quad.scaledTo(source.width, source.height, 1, 1)
     val baseRotation = Rotation.fromDegrees(rotationDegrees)
-    val metadata = PageMetadata(normalizedQuad, baseRotation, isColored)
+    val metadata = PageMetadata(normalizedQuad, baseRotation, colorMode)
     val sourceJpegDeferred = viewModelScope.async(Dispatchers.IO) {
         compressJpeg(source, 90)
     }

app/src/test/java/org/fairscan/app/data/ImageRepositoryTest.kt

@@ -26,6 +26,7 @@ import org.fairscan.app.domain.Rotation.R0
 import org.fairscan.app.domain.Rotation.R180
 import org.fairscan.app.domain.Rotation.R270
 import org.fairscan.app.domain.Rotation.R90
+import org.fairscan.imageprocessing.ColorMode
 import org.fairscan.imageprocessing.Point
 import org.fairscan.imageprocessing.Quad
 import org.junit.Rule
@@ -43,7 +44,7 @@ class ImageRepositoryTest {
     private val testScope = TestScope()
 
     val quad1 = Quad(Point(.01, .02), Point(.1, .03), Point(.11, .12), Point(.03, .09))
-    val metadata1 = PageMetadata(quad1, R90, true)
+    val metadata1 = PageMetadata(quad1, R90, ColorMode.COLOR)
 
     fun getFilesDir(): File {
         if (_filesDir == null) {
@@ -83,7 +84,7 @@ class ImageRepositoryTest {
         assertThat(metadata).isNotNull()
         assertThat(metadata!!.normalizedQuad).isEqualTo(quad1)
         assertThat(metadata.baseRotation).isEqualTo(metadata1.baseRotation)
-        assertThat(metadata.isColored).isEqualTo(metadata1.isColored)
+        assertThat(metadata.autoColorMode).isEqualTo(metadata1.autoColorMode)
     }
 
     @Test
@@ -253,7 +254,9 @@ class ImageRepositoryTest {
         listOf(true, false).forEach { isColored ->
             val metadata = PageV2("1", 0, 0, quad, isColored).toMetadata()
             assertThat(metadata).isNotNull()
-            assertThat(metadata!!.isColored).isEqualTo(isColored)
+            assertThat(metadata!!.autoColorMode).isEqualTo(
+                if (isColored) ColorMode.COLOR else ColorMode.GRAYSCALE
+            )
         }
     }
 

evaluation/src/main/java/org/fairscan/evaluation/ColorDetectionEvaluator.kt

@@ -14,9 +14,10 @@
  */
 package org.fairscan.evaluation
 
+import org.fairscan.imageprocessing.ColorMode
 import org.fairscan.imageprocessing.detectDocumentQuad
 import org.fairscan.imageprocessing.extractDocument
-import org.fairscan.imageprocessing.isColoredDocument
+import org.fairscan.imageprocessing.autoColorMode
 import org.fairscan.imageprocessing.scaledTo
 import org.fairscan.imageprocessing.toImageSize
 import org.opencv.imgcodecs.Imgcodecs
@@ -62,10 +63,10 @@ object ColorDetectionEvaluator {
                 ?.scaledTo(mask.width, mask.height, mat.width(), mat.height())
 
             if (quad == null) continue
-            val isColored = isColoredDocument(mat, mask, quad)
+            val colorMode = autoColorMode(mat, mask, quad)
-            val extracted = extractDocument(mat, quad, 0, isColored, 2_000_000)
+            val extracted = extractDocument(mat, quad, 0, colorMode, 2_000_000)
 
-            val detected = isColored
+            val detected = colorMode == ColorMode.COLOR
 
             nbProcessedImages++
 

evaluation/src/main/java/org/fairscan/evaluation/DatasetEvaluator.kt

@@ -17,7 +17,7 @@ package org.fairscan.evaluation
 import org.fairscan.imageprocessing.Mask
 import org.fairscan.imageprocessing.detectDocumentQuad
 import org.fairscan.imageprocessing.extractDocument
-import org.fairscan.imageprocessing.isColoredDocument
+import org.fairscan.imageprocessing.autoColorMode
 import org.fairscan.imageprocessing.scaledTo
 import org.fairscan.imageprocessing.toImageSize
 import org.opencv.core.Mat
@@ -74,8 +74,8 @@ object DatasetEvaluator {
                 ?.scaledTo(mask.width, mask.height, inputMat.width(), inputMat.height())
 
             val corrected: Mat? = if (quad != null) {
-                val isColored = isColoredDocument(inputMat, mask, quad)
+                val colorMode = autoColorMode(inputMat, mask, quad)
-                extractDocument(inputMat, quad = quad, rotationDegrees = 0, isColored, 2_000_000)
+                extractDocument(inputMat, quad = quad, rotationDegrees = 0, colorMode, 2_000_000)
             } else null
 
             val inputOut = File(outputDir, "${e.name}_input.jpg")

evaluation/src/main/java/org/fairscan/evaluation/ExportQualityEvaluator.kt

@@ -16,7 +16,7 @@ package org.fairscan.evaluation
 
 import org.fairscan.imageprocessing.detectDocumentQuad
 import org.fairscan.imageprocessing.extractDocument
-import org.fairscan.imageprocessing.isColoredDocument
+import org.fairscan.imageprocessing.autoColorMode
 import org.fairscan.imageprocessing.scaledTo
 import org.fairscan.imageprocessing.toImageSize
 import org.opencv.core.MatOfInt
@@ -65,13 +65,13 @@ object ExportQualityEvaluator {
                 continue
             }
 
-            val isColored = isColoredDocument(sourceMat, mask, quad)
+            val colorMode = autoColorMode(sourceMat, mask, quad)
 
             for (quality in qualities) {
 
                 for (maxPixels in maxPixelsList) {
                     val outputMat =
-                        extractDocument(sourceMat, quad, 0, isColored, maxPixels.toLong())
+                        extractDocument(sourceMat, quad, 0, colorMode, maxPixels.toLong())
 
                     val outputFile = File(outputDir, "$imgName-$quality-$maxPixels.jpg")
                     val params = MatOfInt(Imgcodecs.IMWRITE_JPEG_QUALITY, quality)

imageprocessing/src/main/java/org/fairscan/imageprocessing/ColorDetection.kt

@@ -26,7 +26,7 @@ import org.opencv.imgproc.Imgproc
 import org.opencv.imgproc.Imgproc.fillConvexPoly
 import kotlin.math.roundToInt
 
-fun isColoredDocument(
+fun autoColorMode(
     img: Mat,
     mask: Mask,
     quad: Quad,
@@ -34,7 +34,7 @@ fun isColoredDocument(
     proportionThreshold: Double = 0.0003,
     luminanceMin: Double = 40.0,
     luminanceMax: Double = 180.0
-): Boolean {
+): ColorMode {
 
     // Work on a reasonable size (for correct performance)
     val resizedImg = resizeForMaxPixels(img, 1024.0 * 768.0)
@@ -90,10 +90,13 @@ fun isColoredDocument(
     restrictedMask.release()
     docMask.release()
 
-    if (totalPixels == 0) return false
+    if (totalPixels == 0) return ColorMode.GRAYSCALE
 
     val proportion = coloredPixels.toDouble() / totalPixels.toDouble()
-    return proportion > proportionThreshold
+    return if (proportion > proportionThreshold)
+        ColorMode.COLOR
+    else
+        ColorMode.GRAYSCALE
 }
 
 private fun chroma(a: Mat, b: Mat): Mat {

imageprocessing/src/main/java/org/fairscan/imageprocessing/DocumentDetection.kt

@@ -154,7 +154,7 @@ fun extractDocument(
     inputMat: Mat,
     quad: Quad,
     rotationDegrees: Int,
-    isColored: Boolean,
+    colorMode: ColorMode,
     maxPixels: Long,
 ): Mat {
     val widthTop = norm(quad.topLeft, quad.topRight)
@@ -184,7 +184,7 @@ fun extractDocument(
     Imgproc.warpPerspective(inputMat, warped, transform, outputSize)
 
     val resized = resizeForMaxPixels(warped, maxPixels.toDouble())
-    val enhanced = enhanceCapturedImage(resized, isColored)
+    val enhanced = enhanceCapturedImage(resized, colorMode)
     val rotated = rotate(enhanced, rotationDegrees)
 
     warped.release()

imageprocessing/src/main/java/org/fairscan/imageprocessing/PostProcessing.kt

@@ -25,11 +25,15 @@ import org.opencv.imgproc.Imgproc
 import kotlin.math.max
 import kotlin.math.min
 
-fun enhanceCapturedImage(img: Mat, isColored: Boolean): Mat {
+enum class ColorMode {
-    return if (isColored) {
+    COLOR,
-        multiScaleRetinexOnL(img)
+    GRAYSCALE,
-    } else {
+}
-        enhanceGrayscaleImage(img)
+
+fun enhanceCapturedImage(img: Mat, colorMode: ColorMode): Mat {
+    return when (colorMode) {
+        ColorMode.COLOR -> multiScaleRetinexOnL(img)
+        ColorMode.GRAYSCALE -> enhanceGrayscaleImage(img)
     }
 }