[api]: Fix FITS image rescaling. Use the min and max values if is out…

… of range
tiagohm · Apr 6, 2024 · d1f010e · d1f010e
1 parent b28ee23
commit d1f010e
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Showing 4 changed files with 26 additions and 18 deletions.
diff --git a/api/src/main/kotlin/nebulosa/api/image/ImageService.kt b/api/src/main/kotlin/nebulosa/api/image/ImageService.kt
@@ -111,7 +111,6 @@ class ImageService(
         val (autoStretch, shadow, highlight, midtone) = transformation.stretch
         val scnrEnabled = transformation.scnr.channel != null
         val manualStretch = shadow != 0f || highlight != 1f || midtone != 0.5f
-        var stretchParams = ScreenTransformFunction.Parameters(midtone, shadow, highlight)
 
         val shouldBeTransformed = enabled && (autoStretch || manualStretch
                 || transformation.mirrorHorizontal || transformation.mirrorVertical || transformation.invert
@@ -139,11 +138,14 @@ class ImageService(
         val statistics = if (operation == ImageOperation.OPEN) transformedImage.compute(Statistics.GRAY)
         else null
 
+        var stretchParams = ScreenTransformFunction.Parameters.DEFAULT
+
         if (enabled) {
             if (autoStretch) {
                 stretchParams = AutoScreenTransformFunction.compute(transformedImage)
                 transformedImage = ScreenTransformFunction(stretchParams).transform(transformedImage)
             } else if (manualStretch) {
+                stretchParams = ScreenTransformFunction.Parameters(midtone, shadow, highlight)
                 transformedImage = ScreenTransformFunction(stretchParams).transform(transformedImage)
             }
         }

diff --git a/nebulosa-fits/src/main/kotlin/nebulosa/fits/SeekableSourceImageData.kt b/nebulosa-fits/src/main/kotlin/nebulosa/fits/SeekableSourceImageData.kt
@@ -3,10 +3,11 @@ package nebulosa.fits
 import nebulosa.fits.FitsFormat.readPixel
 import nebulosa.image.format.ImageChannel
 import nebulosa.image.format.ImageData
-import nebulosa.image.format.ImageData.Companion.representableRange
 import nebulosa.io.SeekableSource
+import nebulosa.log.loggerFor
 import okio.Buffer
 import okio.Sink
+import kotlin.math.max
 import kotlin.math.min
 
 @Suppress("NOTHING_TO_INLINE")
@@ -20,9 +21,6 @@ internal data class SeekableSourceImageData(
     private val range: ClosedFloatingPointRange<Float>,
 ) : ImageData {
 
-    private val rangeDelta = range.endInclusive - range.start
-    private val rescale = range.start != 0f || range.endInclusive != 1f
-
     @JvmField internal val channelSizeInBytes = (numberOfPixels * bitpix.byteLength).toLong()
     @JvmField internal val totalSizeInBytes = channelSizeInBytes * numberOfChannels
 
@@ -77,6 +75,9 @@ internal data class SeekableSourceImageData(
         var pos = 0
 
         Buffer().use { buffer ->
+            var min = Float.MAX_VALUE
+            var max = Float.MIN_VALUE
+
             while (remainingPixels > 0) {
                 var n = min(PIXEL_COUNT, remainingPixels)
                 val byteCount = n * bitpix.byteLength.toLong()
@@ -90,12 +91,25 @@ internal data class SeekableSourceImageData(
 
                 repeat(n) {
                     val pixel = buffer.readPixel(bitpix)
-                    output[pos++] = if (rescale) pixel.representableRange(range.start, range.endInclusive, rangeDelta)
-                    else pixel
+                    if (pixel < min) min = pixel
+                    if (pixel > max) max = pixel
+                    output[pos++] = pixel
                 }
 
                 remainingPixels -= n
             }
+
+            if (min < 0f || max > 1f) {
+                val rangeMin = min(range.start, min)
+                val rangeMax = max(range.endInclusive, max)
+                val rangeDelta = rangeMax - rangeMin
+
+                LOG.info("rescaling [{}, {}] to [0, 1]. channel={}, delta={}", rangeMin, rangeMax, channel, rangeDelta)
+
+                for (i in output.indices) {
+                    output[i] = (output[i] - rangeMin) / rangeDelta
+                }
+            }
         }
     }
 
@@ -130,5 +144,7 @@ internal data class SeekableSourceImageData(
     companion object {
 
         const val PIXEL_COUNT = 64
+
+        @JvmStatic private val LOG = loggerFor<SeekableSourceImageData>()
     }
 }
diff --git a/nebulosa-image-format/src/main/kotlin/nebulosa/image/format/ImageData.kt b/nebulosa-image-format/src/main/kotlin/nebulosa/image/format/ImageData.kt
@@ -18,14 +18,4 @@ interface ImageData {
     val blue: FloatArray
 
     fun readChannelTo(channel: ImageChannel, output: FloatArray)
-
-    companion object {
-
-        @Suppress("NOTHING_TO_INLINE")
-        inline fun Float.representableRange(rangeMin: Float, rangeMax: Float, rangeDelta: Float = rangeMax - rangeMin): Float {
-            return if (this < rangeMin) 0f
-            else if (this > rangeMax) 1f
-            else (this - rangeMin) / rangeDelta
-        }
-    }
 }
diff --git a/...image/src/main/kotlin/nebulosa/image/algorithms/transformation/ScreenTransformFunction.kt b/...image/src/main/kotlin/nebulosa/image/algorithms/transformation/ScreenTransformFunction.kt
@@ -23,7 +23,7 @@ data class ScreenTransformFunction(
 
         companion object {
 
-            @JvmStatic val EMPTY = Parameters()
+            @JvmStatic val DEFAULT = Parameters()
         }
     }
-Original file line number
+Diff line change
@@ Expand Up / @@ -23,7 +23,7 @@ data class ScreenTransformFunction( @@
             companion object {
-                @JvmStatic val EMPTY = Parameters()
+                @JvmStatic val DEFAULT = Parameters()
             }
         }
@@ Expand Down @@