diff --git a/imagescrollareagl.cpp b/imagescrollareagl.cpp
index f09e299..e3d76f4 100644
--- a/imagescrollareagl.cpp
+++ b/imagescrollareagl.cpp
@@ -113,7 +113,19 @@ void ImageWidget::setImage(std::shared_ptr<RawImage> image, int index)
     m_image->generateMipMaps();
     qDebug() << "setImage" << timer.elapsed();
 
-
+    m_unit_scale[0] = 1.0f;
+    m_unit_scale[1] = 0.0f;
+    auto &stats = image->imageStats();
+    if(image->type() == RawImage::FLOAT32 || image->type() == RawImage::FLOAT64)
+    {
+        float min = *std::min_element(stats.m_min, stats.m_min + 4);
+        float max = *std::max_element(stats.m_max, stats.m_max + 4);
+        if(min < 0.0f || max > 1.0f)
+        {
+            m_unit_scale[0] = 1.0f / (max - min);
+            m_unit_scale[1] = min * m_unit_scale[0];
+        }
+    }
 
     if(m_debayerTex)
     {
@@ -363,6 +375,7 @@ void ImageWidget::paintGL()
         m_program->setUniformValue("viewport", (float)width(), (float)height());
         m_program->setUniformValue("offset", std::floor(dx), std::floor(dy));
         m_program->setUniformValueArray("mtf_param", m_mtfParams.blackPoint, 3, 3);
+        m_program->setUniformValue("unit_scale", m_unit_scale[0], m_unit_scale[1]);
         m_program->setUniformValue("zoom", 1.0f/m_scale);
         m_program->setUniformValue("bw", m_bwImg && !m_superpixel);
         m_program->setUniformValue("false_color", m_falseColor && m_bwImg);
diff --git a/imagescrollareagl.h b/imagescrollareagl.h
index 29fc441..07f56fa 100644
--- a/imagescrollareagl.h
+++ b/imagescrollareagl.h
@@ -48,6 +48,7 @@ class ImageWidget : public QOpenGLWidget
     int m_imgWidth = -1, m_imgHeight = -1;
     int m_currentImg = 0;
     MTFParam m_mtfParams;
+    float m_unit_scale[2] = {1.0f, 0.0f}; // scale and offset
     float m_dx = 0, m_dy = 0;
     float m_scale = 1.0f;
     int m_scaleStop = 0;
diff --git a/shaders/image.frag b/shaders/image.frag
index d0410dd..a1bcc09 100644
--- a/shaders/image.frag
+++ b/shaders/image.frag
@@ -2,6 +2,7 @@
 
 uniform sampler2D qt_Texture0;
 uniform vec3 mtf_param[3];
+uniform vec2 unit_scale;
 uniform bool bw;
 uniform bool invert;
 uniform bool srgb;
@@ -46,6 +47,7 @@ vec3 checker()
 void main(void)
 {
     color = texture(qt_Texture0, qt_TexCoord0);
+    color.rgb = color.rgb * unit_scale.x + unit_scale.y;
     if(bw)color = color.rrra;
     color = MTF(color, vec4(mtf_param[0], 0.0), vec4(mtf_param[1], 0.5), vec4(mtf_param[2], 1.0));
     if(false_color)color.rgb = falsecolor(color.r);