{"record":{"id":"864a0f9849060049","repo":"Yalantis/uCrop","slug":"cimg-appname-math-parser-cimg-s-s-s-type-864a0f","errorCode":null,"errorMessage":"[cimg_appname_math_parser] CImg<%s>::%s: %s: Type of first arguments ('%s') does not match with third argument 'nb_channelsX=%u', in expression '%s'.","messagePattern":"\\[cimg_appname_math_parser\\] CImg<(.+?)>::(.+?): (.+?): Type of first arguments \\('(.+?)'\\) does not match with third argument 'nb_channelsX=%u', in expression '(.+?)'\\.","errorType":"exception","errorClass":"CImgArgumentException","httpStatus":null,"severity":"error","filePath":"ucrop/src/main/jni/CImg.h","lineNumber":22511,"sourceCode":"                arg3 = compile(s2,s1,depth1,0,block_flags);\n                if (s1<se1) {\n                  s2 = ++s1; while (s2<se1 && (*s2!=',' || level[s2 - expr._data]!=clevel1)) ++s2;\n                  arg4 = compile(s1,s2,depth1,0,block_flags);\n                  arg5 = s2<se1?compile(++s2,se1,depth1,0,block_flags):0;\n                }\n              }\n              _cimg_mp_check_type(arg1,1,2,0);\n              _cimg_mp_check_type(arg2,2,2,0);\n              _cimg_mp_check_const_scalar(arg3,3,3);\n              _cimg_mp_check_const_scalar(arg4,4,3);\n              _cimg_mp_check_type(arg5,5,1,0);\n              p1 = size(arg1);\n              p2 = size(arg2);\n              arg3 = (unsigned int)mem[arg3];\n              arg4 = (unsigned int)mem[arg4];\n              if (p1%arg3) {\n                _cimg_mp_strerr;\n                throw CImgArgumentException(\"[\" cimg_appname \"_math_parser] \"\n                                            \"CImg<%s>::%s: %s: Type of first arguments ('%s') \"\n                                            \"does not match with third argument 'nb_channelsX=%u', \"\n                                            \"in expression '%s'.\",\n                                            pixel_type(),_cimg_mp_calling_function,s_op,\n                                            s_type(arg1)._data,arg3,s0);\n              }\n              if (p2%arg4) {\n                _cimg_mp_strerr;\n                throw CImgArgumentException(\"[\" cimg_appname \"_math_parser] \"\n                                            \"CImg<%s>::%s: %s: Type of second arguments ('%s') \"\n                                            \"does not match with fourth argument 'nb_channelsP=%u', \"\n                                            \"in expression '%s'.\",\n                                            pixel_type(),_cimg_mp_calling_function,s_op,\n                                            s_type(arg2)._data,arg4,s0);\n              }\n              pos = vector(p1*arg4);\n              CImg<ulongT>::vector((ulongT)mp_map,pos,arg1,arg2,p1,p2,arg3,arg4,arg5).move_to(code);\n              return_comp = true;","sourceCodeStart":22493,"sourceCodeEnd":22529,"githubUrl":"https://github.com/Yalantis/uCrop/blob/f788b534b48c144edf786c8cddbf0e029e637804/ucrop/src/main/jni/CImg.h#L22493-L22529","documentation":"Per-pixel/channel operations in the parser that take both data vectors and channel counts check that the first argument's size p1 is divisible by nb_channelsX (arg3). If p1 % arg3 != 0, CImg throws this error naming the first argument's type and the channel count, because the data cannot be grouped into complete channel tuples.","triggerScenarios":"Calling a multi-channel expression function (e.g. color-space conversion taking nb_channelsX) where the first input vector's length is not a multiple of the specified X channel count, e.g. 8 values with nb_channelsX=3.","commonSituations":"Converting between RGB and XYZ/Lab with stale channel counts; feeding grayscale data (1 channel) while specifying 3; truncated or padded buffers from earlier processing steps.","solutions":["Ensure input X data length is an exact multiple of nb_channelsX before the call","Pass the channel count matching your actual data layout (1 for gray, 3 for RGB, 4 for RGBA)","Pad or truncate the input vector to a multiple of the channel count","Derive nb_channelsX from the source image's spectrum() instead of hard-coding"],"exampleFix":"// before\nimg.fill(\"convert([v0,...,v7], 3, ...)\"); // 8 not divisible by 3\n// after\nimg.fill(\"convert([v0,...,v8], 3, ...)\"); // 9 divisible by 3","handlingStrategy":"validation","validationCode":"void checkChannelsX(double[] x, int nbChannelsX) {\n  if (x.length % nbChannelsX != 0)\n    throw new IllegalArgumentException(\"Input X size \" + x.length + \" not a multiple of nb_channelsX=\" + nbChannelsX);\n}","typeGuard":null,"tryCatchPattern":"try { img.fill(expr); } catch (CImgArgumentException e) { if (e.getMessage().contains(\"nb_channelsX\")) { /* fix channel count or input length */ } throw e; }","preventionTips":["Derive channel counts from source.spectrum() rather than literals","Validate x.length % nb_channelsX == 0 before the call","Keep channel-count constants shared between all inputs of the same operation"],"tags":["cimg","math-parser","channels","shape-mismatch"],"backgroundTag":"shape-mismatch","analyzedSha":"f788b534b48c144edf786c8cddbf0e029e637804","analyzedAt":"2026-09-08T08:36:04.887Z","contentChangedAt":"2026-09-08T08:36:04.887Z","schemaVersion":2},"datasetVersion":"2026-09-14T05:17:10.506Z"}