Add a 'plainclip' filter.

This is useful for doing color manipulation on output renders, either by
hand in color grading software or automatically using renormalization
based on image statistics.

cuburn/code/filters.py

@@ -328,6 +328,28 @@ smearclip(float4 *pixbuf, const float4 *smearbuf,
 }
 ''')
 
+plaincliplib = devlib(deps=[yuvlib], defs=r'''
+__global__ void
+plainclip(float4 *pixbuf, float gamma_m_1, float linrange, float lingam,
+        float brightness) {
+    GET_IDX(i);
+    float4 pix = pixbuf[i];
+
+    if (pix.w <= 0) {
+        pixbuf[i] = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
+        return;
+    }
+
+    float ls = powf(pix.w, gamma_m_1);
+    if (pix.w < linrange) {
+        float frac = pix.w / linrange;
+        ls = (1.0f - frac) * lingam + frac * ls;
+    }
+    scale_float4(pix, ls * brightness);
+    pixbuf[i] = pix;
+}
+''')
+
 colorcliplib = devlib(deps=[yuvlib], defs=r'''
 __global__ void
 colorclip(float4 *pixbuf, float vibrance, float highpow,

cuburn/filters.py

@@ -180,6 +180,15 @@ class ColorClip(Filter, ClsMod):
         launch2('colorclip', self.mod, stream, dim,
                 fb.d_front, vib, hipow, gam, lin, lingam)
 
+@Filter.register('plainclip')
+class PlainClip(Filter, ClsMod):
+    lib = code.filters.plaincliplib
+    def apply(self, fb, gprof, params, dim, tc, stream=None):
+        gam, lin, lingam = calc_lingam(gprof.filters.colorclip, tc)
+        launch2('plainclip', self.mod, stream, dim,
+                fb.d_front, f32(gam-1), lin, lingam,
+                f32(gprof.filters.plainclip.brightness(tc)))
+
 
 @Filter.register('logencode')
 class LogEncode(Filter, ClsMod):

cuburn/genome/specs.py

@@ -53,6 +53,7 @@ filters = (
     }
   , 'haloclip': {}
   , 'smearclip': {'width': scalespline(0.7, d='Spatial stdev of filter')}
+  , 'plainclip': {'brightness': scalespline(1.0, d='Linear brightness')}
   , 'logscale': {'brightness': scalespline(4, d='Log-scale brightness')}
   , 'logencode': {'degamma': scalespline(2.2)}
   , 'yuv': {}