Add additional colormaps

shaders/image.frag

@@ -1,5 +1,6 @@
 uniform sampler2D qt_Texture0;
 uniform sampler3D lut_table;
+uniform sampler1DArray colormap;
 uniform vec3 mtf_param[3];
 uniform vec2 unit_scale;
 uniform bool bw;
@@ -7,6 +8,7 @@ uniform bool invert;
 uniform bool srgb;
 uniform bool false_color;
 uniform int filtering;
+uniform int colormapIdx;
 in vec2 qt_TexCoord0;
 layout(location = 0) out vec4 color;
 
@@ -26,17 +28,9 @@ vec4 MTF(vec4 x, vec4 low, vec4 mid, vec4 high)
 
 vec3 falsecolor(float color)
 {
-    const vec3 pallete[] = vec3[](
-            vec3(1.0, 0.0, 1.0), //magneta
-            vec3(0.0, 0.0, 1.0), //blue
-            vec3(0.0, 1.0, 1.0), //cyan
-            vec3(0.0, 1.0, 0.0), //green
-            vec3(1.0, 1.0, 0.0), //yellow
-            vec3(1.0, 0.0, 0.0), vec3(1.0, 0.0, 0.0));//red
-    color *= 5.0;
-    int i = int(color);
-    float f = fract(color);
-    return mix(pallete[i], pallete[i+1], f);// * (f * 0.5 + 0.5);
+    color *= 255.0 / 256.0;
+    color += 0.5 / 256.0;
+    return texture(colormap, vec2(color, colormapIdx)).rgb;
 }
 
 vec3 checker()