Store page metadata after capture

app/src/main/java/org/fairscan/app/MainViewModel.kt

@@ -103,7 +103,8 @@ class MainViewModel(val imageRepository: ImageRepository, launchMode: LaunchMode
         viewModelScope.launch {
             imageRepository.add(
                 compressJpeg(capturedPage.page, 75),
-                compressJpeg(capturedPage.source, 90)
+                compressJpeg(capturedPage.source, 90),
+                capturedPage.metadata,
             )
             _pageIds.value = imageRepository.imageIds()
         }

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

@@ -25,4 +25,21 @@ data class DocumentMetadata(
 @Serializable
 data class Page(
     val file: String,
+    val quad: NormalizedQuad? = null,
+    val rotationDegrees: Int = 0,
+    val isColored: Boolean? = null
+)
+
+@Serializable
+data class NormalizedQuad(
+    val topLeft: PointD,
+    val topRight: PointD,
+    val bottomRight: PointD,
+    val bottomLeft: PointD
+)
+
+@Serializable
+data class PointD(
+    val x: Double,
+    val y: Double
 )

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

@@ -14,9 +14,12 @@
  */
 package org.fairscan.app.data
 
-import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.PersistentList
-import kotlinx.collections.immutable.toImmutableList
+import kotlinx.collections.immutable.toPersistentList
 import kotlinx.serialization.json.Json
+import org.fairscan.app.domain.PageMetadata
+import org.fairscan.imageprocessing.Point
+import org.fairscan.imageprocessing.Quad
 import java.io.File
 
 const val SOURCE_DIR_NAME = "sources"
@@ -43,30 +46,33 @@ class ImageRepository(
 
     private val metadataFile = File(scanDir, "document.json")
 
-    private var fileNames: MutableList<String> =
+    private var pages: MutableList<Page> = loadPages()
-        loadFileNames()
 
-    private fun loadFileNames(): MutableList<String> {
+    private fun loadPages(): MutableList<Page> {
-        val filesOnDisk: Set<String> = scanDir.listFiles()
+        val filesOnDisk = scanDir.listFiles()
             ?.filter { it.extension == "jpg" }
             ?.map { it.name }
             ?.toSet()
             ?: emptySet()
 
-        val metadataFiles: List<String>? = loadMetadata()
+        val metadataPages = loadMetadata()?.pages
-            ?.pages
-            ?.map { it.file }
 
         return when {
-            metadataFiles != null -> metadataFiles
+            metadataPages != null ->
-                .filter { it in filesOnDisk }
+                metadataPages
+                    .filter { it.file in filesOnDisk }
                     .toMutableList()
-            else -> filesOnDisk
+            else ->
+                filesOnDisk
                     .sorted()
+                    .map { Page(file = it) }
                     .toMutableList()
         }
     }
 
+    private fun indexOfPage(id: String): Int =
+        pages.indexOfFirst { it.file == id }
+
     private fun loadMetadata(): DocumentMetadata? =
         if (metadataFile.exists()) {
             runCatching {
@@ -75,19 +81,33 @@ class ImageRepository(
         } else null
 
     private fun saveMetadata() {
-        val metadata = DocumentMetadata(version = 1, pages = fileNames.map { id -> Page(id) })
+        val metadata = DocumentMetadata(version = 1, pages = pages)
         metadataFile.writeText(Json.encodeToString(metadata))
     }
 
-    fun imageIds(): ImmutableList<String> = fileNames.toImmutableList()
+    fun imageIds(): PersistentList<String> =
+        pages.map { it.file }.toPersistentList()
 
-    fun add(pageBytes: ByteArray, sourceBytes: ByteArray? = null) {
+    fun getPageMetadata(id: String): PageMetadata? {
+        val index = indexOfPage(id)
+        if (index < 0) return null
+        return pages[index].toMetadata()
+    }
+
+    fun add(pageBytes: ByteArray, sourceBytes: ByteArray, metadata: PageMetadata) {
         val fileName = "${System.currentTimeMillis()}.jpg"
         val file = File(scanDir, fileName)
         file.writeBytes(pageBytes)
         writeThumbnail(file)
-        sourceBytes?.let { File(sourceDir, fileName).writeBytes(sourceBytes) }
+        File(sourceDir, fileName).writeBytes(sourceBytes)
-        fileNames.add(fileName)
+        pages.add(
+            Page(
+                file = fileName,
+                quad = metadata.normalizedQuad.toSerializable(),
+                rotationDegrees = metadata.rotationDegrees,
+                isColored = metadata.isColored
+            )
+        )
         saveMetadata()
     }
 
@@ -106,9 +126,10 @@ class ImageRepository(
             val rotatedFile = File(scanDir, rotatedId)
             transformations.rotate(originalFile, rotatedFile, clockwise)
             if (rotatedFile.exists()) {
-                val index = fileNames.indexOf(id)
+                val index = indexOfPage(id)
                 if (index >= 0) {
-                    fileNames[index] = rotatedId
+                    val oldPage = pages[index]
+                    pages[index] = oldPage.copy(file = rotatedId)
                     saveMetadata()
                 }
                 delete(id)
@@ -143,21 +164,24 @@ class ImageRepository(
     private fun getThumbnailFile(id: String): File = File(thumbnailDir, id)
 
     fun movePage(id: String, newIndex: Int) {
-        if (!fileNames.remove(id)) return
+        val index = indexOfPage(id)
-        val safeIndex = newIndex.coerceIn(0, fileNames.size)
+        if (index < 0) return
-        fileNames.add(safeIndex, id)
+
+        val page = pages.removeAt(index)
+        val safeIndex = newIndex.coerceIn(0, pages.size)
+        pages.add(safeIndex, page)
         saveMetadata()
     }
 
     fun delete(id: String) {
         File(scanDir, id).delete()
         getThumbnailFile(id).delete()
-        fileNames.remove(id)
+        pages.removeAll { it.file == id }
         saveMetadata()
     }
 
     fun clear() {
-        fileNames.clear()
+        pages.clear()
         thumbnailDir.listFiles()?.forEach {
             file -> file.delete()
         }
@@ -170,3 +194,24 @@ class ImageRepository(
         saveMetadata() // "empty" json file
     }
 }
+
+fun Quad.toSerializable(): NormalizedQuad =
+    NormalizedQuad(
+        topLeft = PointD(topLeft.x, topLeft.y),
+        topRight = PointD(topRight.x, topRight.y),
+        bottomRight = PointD(bottomRight.x, bottomRight.y),
+        bottomLeft = PointD(bottomLeft.x, bottomLeft.y)
+    )
+
+fun NormalizedQuad.toQuad(): Quad =
+    Quad(
+        Point(topLeft.x, topLeft.y),
+        Point(topRight.x, topRight.y),
+        Point(bottomRight.x, bottomRight.y),
+        Point(bottomLeft.x, bottomLeft.y)
+)
+
+fun Page.toMetadata(): PageMetadata? {
+    if (quad == null || isColored == null) return null
+    return PageMetadata(quad.toQuad(), rotationDegrees, isColored)
+}

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

@@ -19,5 +19,6 @@ import android.graphics.Bitmap
 
 data class CapturedPage(
     val page: Bitmap,
-    val source: Bitmap
+    val source: Bitmap,
+    val metadata: PageMetadata,
 )

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

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2025 Pierre-Yves Nicolas
+ *
+ * This program is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation, either version 3 of the License, or (at your option)
+ * any later version.
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+package org.fairscan.app.domain
+
+import org.fairscan.imageprocessing.Quad
+
+data class PageMetadata(
+    val normalizedQuad: Quad,
+    val rotationDegrees: Int,
+    val isColored: Boolean,
+)

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

@@ -85,6 +85,7 @@ import kotlinx.coroutines.delay
 import org.fairscan.app.MainViewModel
 import org.fairscan.app.R
 import org.fairscan.app.domain.CapturedPage
+import org.fairscan.app.domain.PageMetadata
 import org.fairscan.app.ui.Navigation
 import org.fairscan.app.ui.Screen
 import org.fairscan.app.ui.components.CameraPermissionState
@@ -95,6 +96,8 @@ 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.Point
+import org.fairscan.imageprocessing.Quad
 
 const val CAPTURED_IMAGE_DISPLAY_DURATION = 1500L
 const val ANIMATION_DURATION = 200
@@ -461,11 +464,14 @@ fun CameraScreenPreview() {
 @Preview(showBackground = true, showSystemUi = true)
 @Composable
 fun CameraScreenPreviewWithProcessedImage() {
+    val p = Point(0 , 0)
+    val quad = Quad(p, p, p, p)
     ScreenPreview(CaptureState.CapturePreview(
         debugImage("uncropped/img01.jpg"),
         CapturedPage(
             debugImage("gallica.bnf.fr-bpt6k5530456s-1.jpg"),
-            debugImage("gallica.bnf.fr-bpt6k5530456s-1.jpg"))))
+            debugImage("gallica.bnf.fr-bpt6k5530456s-1.jpg"),
+            PageMetadata(quad, 0, false))))
 }
 
 @Preview(showBackground = true, widthDp = 640, heightDp = 320)

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

@@ -32,6 +32,7 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 import org.fairscan.app.AppContainer
 import org.fairscan.app.domain.CapturedPage
+import org.fairscan.app.domain.PageMetadata
 import org.fairscan.imageprocessing.Mask
 import org.fairscan.imageprocessing.Quad
 import org.fairscan.imageprocessing.detectDocumentQuad
@@ -118,9 +119,9 @@ class CameraViewModel(appContainer: AppContainer): ViewModel() {
         if (imageProxy != null) {
             viewModelScope.launch {
                 val source = imageProxy.toBitmap()
-                val processed = processCapturedImage(source, imageProxy.imageInfo.rotationDegrees)
+                val page = processCapturedImage(source, imageProxy.imageInfo.rotationDegrees)
                 imageProxy.close()
-                onCaptureProcessed(processed?.let { CapturedPage(processed, source) })
+                onCaptureProcessed(page)
             }
         } else {
             onCaptureProcessed(null)
@@ -128,11 +129,11 @@ class CameraViewModel(appContainer: AppContainer): ViewModel() {
     }
 
     private suspend fun processCapturedImage(
-        bitmap: Bitmap,
+        source: Bitmap,
         rotationDegrees: Int
-    ): Bitmap? = withContext(Dispatchers.IO) {
+    ): CapturedPage? = withContext(Dispatchers.IO) {
-        var corrected: Bitmap? = null
+        var result: CapturedPage? = null
-        val segmentation = imageSegmentationService.runSegmentationAndReturn(bitmap, 0)
+        val segmentation = imageSegmentationService.runSegmentationAndReturn(source, 0)
         if (segmentation != null) {
             val mask = segmentation.segmentation
             var quad = detectDocumentQuad(mask, isLiveAnalysis = false)
@@ -152,11 +153,11 @@ class CameraViewModel(appContainer: AppContainer): ViewModel() {
                 }
             }
             if (quad != null) {
-                val resizedQuad = quad.scaledTo(mask.width, mask.height, bitmap.width, bitmap.height)
+                val resizedQuad = quad.scaledTo(mask.width, mask.height, source.width, source.height)
-                corrected = extractDocumentFromBitmap(bitmap, resizedQuad, rotationDegrees, mask)
+                result = extractDocumentFromBitmap(source, resizedQuad, rotationDegrees, mask)
             }
         }
-        return@withContext corrected
+        return@withContext result
     }
 
     fun addProcessedImage() {
@@ -187,17 +188,22 @@ sealed class CaptureState {
     ) : CaptureState()
 }
 
-fun extractDocumentFromBitmap(image: Bitmap, quad: Quad, rotationDegrees: Int, mask: Mask): Bitmap {
+fun extractDocumentFromBitmap(
+    source: Bitmap, quad: Quad, rotationDegrees: Int, mask: Mask
+): CapturedPage {
     val rgba = Mat()
-    Utils.bitmapToMat(image, rgba)
+    Utils.bitmapToMat(source, rgba)
     val bgr = Mat()
     Imgproc.cvtColor(rgba, bgr, Imgproc.COLOR_RGBA2BGR) // CV_8UC4 → CV_8UC3
     rgba.release()
-    val outBgr = extractDocument(bgr, quad, rotationDegrees, mask)
+    val page = extractDocument(bgr, quad, rotationDegrees, mask)
+    val outBgr = page.image
     bgr.release()
     val outBitmap = toBitmap(outBgr)
     outBgr.release()
-    return outBitmap
+    val normalizedQuad = quad.scaledTo(source.width, source.height, 1, 1)
+    val metadata = PageMetadata(normalizedQuad, rotationDegrees, page.pageAnalysis.isColored)
+    return CapturedPage(outBitmap, source, metadata)
 }
 
 fun toBitmap(bgr: Mat): Bitmap {

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

@@ -15,7 +15,9 @@
 package org.fairscan.app.data
 
 import org.assertj.core.api.Assertions.assertThat
-import org.fairscan.app.data.ImageTransformations
+import org.fairscan.app.domain.PageMetadata
+import org.fairscan.imageprocessing.Point
+import org.fairscan.imageprocessing.Quad
 import org.junit.Rule
 import org.junit.Test
 import org.junit.rules.TemporaryFolder
@@ -28,6 +30,9 @@ class ImageRepositoryTest {
 
     private var _filesDir: File? = null
 
+    val quad1 = Quad(Point(.01, .02), Point(.1, .03), Point(.11, .12), Point(.03, .09))
+    val metadata1 = PageMetadata(quad1, 90, true)
+
     fun getFilesDir(): File {
         if (_filesDir == null) {
             _filesDir = folder.newFolder("files_dir")
@@ -52,17 +57,25 @@ class ImageRepositoryTest {
         val repo = repo()
         assertThat(repo.imageIds()).isEmpty()
         val bytes = byteArrayOf(101, 102, 103)
-        repo.add(bytes)
+        repo.add(bytes, byteArrayOf(51), metadata1)
         assertThat(repo.imageIds()).hasSize(1)
-        assertThat(repo.getContent(repo.imageIds()[0])).isEqualTo(bytes)
+        val id = repo.imageIds()[0]
-        assertThat(repo.getThumbnail(repo.imageIds()[0])).isEqualTo(byteArrayOf(101))
+        assertThat(repo.getContent(id)).isEqualTo(bytes)
+        assertThat(repo.getThumbnail(id)).isEqualTo(byteArrayOf(101))
+
+        assertThat(repo().getPageMetadata("x")).isNull()
+        val metadata = repo.getPageMetadata(id)
+        assertThat(metadata).isNotNull()
+        assertThat(metadata!!.normalizedQuad).isEqualTo(quad1)
+        assertThat(metadata.rotationDegrees).isEqualTo(metadata1.rotationDegrees)
+        assertThat(metadata.isColored).isEqualTo(metadata1.isColored)
     }
 
     @Test
     fun delete_image() {
         val repo = repo()
         val bytes = byteArrayOf(101, 102, 103)
-        repo.add(bytes)
+        repo.add(bytes, byteArrayOf(51), metadata1)
         assertThat(repo.imageIds()).hasSize(1)
         repo.delete(repo.imageIds()[0])
         assertThat(repo.imageIds()).isEmpty()
@@ -106,7 +119,7 @@ class ImageRepositoryTest {
     fun `clear should delete pages`() {
         val bytes = byteArrayOf(101, 102, 103)
         val repo1 = repo()
-        repo1.add(bytes)
+        repo1.add(bytes, byteArrayOf(51), metadata1)
         assertThat(repo1.imageIds()).isNotEmpty()
         repo1.clear()
         assertThat(repo1.imageIds()).isEmpty()
@@ -123,7 +136,7 @@ class ImageRepositoryTest {
     @Test
     fun rotate() {
         val repo = repo()
-        repo.add(byteArrayOf(101, 102, 103))
+        repo.add(byteArrayOf(101, 102, 103), byteArrayOf(51), metadata1)
         val id0 = repo.imageIds().last()
         val baseId = id0.substring(0, id0.length - 4)
 
@@ -151,9 +164,9 @@ class ImageRepositoryTest {
     @Test
     fun movePage() {
         val repo = repo()
-        repo.add(byteArrayOf(101))
+        repo.add(byteArrayOf(101), byteArrayOf(51), metadata1)
         Thread.sleep(1L) // to avoid file name clashes
-        repo.add(byteArrayOf(110))
+        repo.add(byteArrayOf(110), byteArrayOf(51), metadata1)
         val id0 = repo.imageIds().first()
         val id1 = repo.imageIds().last()
         repo.movePage(id1, 0)
@@ -162,4 +175,18 @@ class ImageRepositoryTest {
         val repo2 = repo()
         assertThat(repo2.imageIds()).containsExactly(id1, id0)
     }
+
+    @Test
+    fun metadata() {
+        val quad = quad1.toSerializable()
+
+        assertThat(Page("f1", null, 0, true).toMetadata()).isNull()
+        assertThat(Page("f1", quad, 0, null).toMetadata()).isNull()
+
+        listOf(true, false).forEach { isColored ->
+            val metadata = Page("f1", quad, 0, isColored).toMetadata()
+            assertThat(metadata).isNotNull()
+            assertThat(metadata!!.isColored).isEqualTo(isColored)
+        }
+    }
 }

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

@@ -14,11 +14,10 @@
  */
 package org.fairscan.evaluation
 
+import org.fairscan.imageprocessing.ExtractedDocument
 import org.fairscan.imageprocessing.detectDocumentQuad
 import org.fairscan.imageprocessing.extractDocument
-import org.fairscan.imageprocessing.isColoredDocument
 import org.fairscan.imageprocessing.scaledTo
-import org.opencv.core.Mat
 import org.opencv.imgcodecs.Imgcodecs
 import java.io.File
 
@@ -61,11 +60,11 @@ object ColorDetectionEvaluator {
             val quad = detectDocumentQuad(mask, isLiveAnalysis = false)
                 ?.scaledTo(mask.width, mask.height, mat.width(), mat.height())
 
-            val document: Mat = if (quad != null) {
+            val extracted: ExtractedDocument = if (quad != null) {
                 extractDocument(mat, quad, 0, mask)
             } else continue
 
-            val detected = isColoredDocument(mat, mask, quad)
+            val detected = extracted.pageAnalysis.isColored
 
             nbProcessedImages++
 
@@ -73,7 +72,7 @@ object ColorDetectionEvaluator {
             Imgcodecs.imwrite(inputOut.absolutePath, mat)
 
             val outputOut = File(outputDir, "${imgName}_output.jpg")
-            Imgcodecs.imwrite(outputOut.absolutePath, document)
+            Imgcodecs.imwrite(outputOut.absolutePath, extracted.image)
 
             results += ColorResult(
                 imgName,

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

@@ -71,7 +71,7 @@ object DatasetEvaluator {
                 ?.scaledTo(mask.width, mask.height, inputMat.width(), inputMat.height())
 
             val corrected: Mat? = if (quad != null) {
-                extractDocument(inputMat, quad = quad, rotationDegrees = 0, mask)
+                extractDocument(inputMat, quad = quad, rotationDegrees = 0, mask).image
             } else null
 
             val inputOut = File(outputDir, "${e.name}_input.jpg")

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

@@ -32,6 +32,15 @@ interface Mask {
     fun toMat(): Mat
 }
 
+data class PageAnalysis(
+    val isColored: Boolean,
+)
+
+data class ExtractedDocument(
+    val image: Mat,
+    val pageAnalysis: PageAnalysis,
+)
+
 fun detectDocumentQuad(mask: Mask, isLiveAnalysis: Boolean, minQuadAreaRatio: Double = 0.02): Quad? {
     val mat = mask.toMat()
     val (biggest: MatOfPoint2f?, area) = biggestContour(mat)
@@ -117,7 +126,7 @@ fun extractDocument(
     quad: Quad,
     rotationDegrees: Int,
     mask: Mask,
-): Mat {
+): ExtractedDocument {
     val widthTop = norm(quad.topLeft, quad.topRight)
     val widthBottom = norm(quad.bottomLeft, quad.bottomRight)
     val targetWidth = (widthTop + widthBottom) / 2
@@ -134,14 +143,14 @@ fun extractDocument(
     )
     val dstPoints = MatOfPoint2f(
         org.opencv.core.Point(0.0, 0.0),
-        org.opencv.core.Point(targetWidth.toDouble(), 0.0),
+        org.opencv.core.Point(targetWidth, 0.0),
-        org.opencv.core.Point(targetWidth.toDouble(), targetHeight.toDouble()),
+        org.opencv.core.Point(targetWidth, targetHeight),
-        org.opencv.core.Point(0.0, targetHeight.toDouble())
+        org.opencv.core.Point(0.0, targetHeight)
     )
     val transform = Imgproc.getPerspectiveTransform(srcPoints, dstPoints)
 
     val outputMat = Mat()
-    val outputSize = Size(targetWidth.toDouble(), targetHeight.toDouble())
+    val outputSize = Size(targetWidth, targetHeight)
     Imgproc.warpPerspective(inputMat, outputMat, transform, outputSize)
 
     val resized = resize(outputMat, 1500.0)
@@ -149,7 +158,7 @@ fun extractDocument(
     val enhanced = enhanceCapturedImage(resized, isColored)
     val rotated = rotate(enhanced, rotationDegrees)
 
-    return rotated
+    return ExtractedDocument(rotated, PageAnalysis(isColored))
 }
 
 fun resize(original: Mat, targetMax: Double): Mat {