def test(self): i = IECore.TIFFImageReader( os.path.dirname(__file__) + "/images/a.tif").read() i["A"] = i["Y"] del i["Y"] t = IECoreGL.AlphaTexture(i, False) ii = t.imagePrimitive() res = IECore.ImageDiffOp()(imageA=i, imageB=ii, maxError=0.001, skipMissingChannels=False) self.failIf(res.value)