Analysis of the realization of Im2col in Caffe

Here, I am the Caffe in the im2col of the parsing process directly pulled out, using C + + output, easy to understand. The code is as follows:

1#include <iostream>2 3 using namespacestd;4 5 BOOLIs_a_ge_zero_and_a_lt_b (intAintb)6 {7     if(a>=0&& a <b)return true;8     return false;9 }Ten  One voidIM2COL_CPU (Const float* Data_im,Const intchannels, A     Const intHeightConst intWidthConst intKernel_h,Const intKernel_w, -     Const intPad_h,Const intPad_w, -     Const intStride_h,Const intStride_w, the     Const intDilation_h,Const intDilation_w, -     float*Data_col) { -   Const intOutput_h = (height +2* Pad_h- -(Dilation_h * (Kernel_h-1) +1))/Stride_h +1; +   Const intOutput_w = (width +2* Pad_w- -(Dilation_w * (Kernel_w-1) +1))/Stride_w +1; +   Const intchannel_size = Height *width; A    for(intChannel = channels; channel--; Data_im + =channel_size) { at      for(intKernel_row =0; Kernel_row < Kernel_h; kernel_row++) { -        for(intKernel_col =0; Kernel_col < Kernel_w; kernel_col++) { -         intInput_row =-pad_h + Kernel_row *Dilation_h; -          for(intOutput_rows = Output_h; Output_rows; output_rows--) { -           if(!is_a_ge_zero_and_a_lt_b (input_row, height)) { -              for(intOutput_cols = Output_w; Output_cols; output_cols--) { in* (data_col++) =0; -             } to}Else { +             intInput_col =-pad_w + Kernel_col *Dilation_w; -              for(intOutput_col = Output_w; Output_col; output_col--) { the               if(Is_a_ge_zero_and_a_lt_b (input_col, width)) { ** (data_col++) = Data_im[input_row * Width +Input_col]; $}Else {Panax Notoginseng* (data_col++) =0; -               } theInput_col + =Stride_w; +             } A           } theInput_row + =Stride_h; +         } -       } $     } $   } - } -  the  - intMain ()Wuyi { the      float*Data_im; -     intheight=5; Wu     intWidth=5;  -     intKernel_h=3;  About     intkernel_w=3; $     intPad_h=1;  -     intpad_w=1; -     intStride_h=1;  -     intstride_w=1; A     intDilation_h=1;  +     intdilation_w=1; the     float*Data_col; -     intChannels =3; $     Const intOutput_h = (height +2* Pad_h- the(Dilation_h * (Kernel_h-1) +1))/Stride_h +1; the       Const intOutput_w = (width +2* Pad_w- the(Dilation_w * (Kernel_w-1) +1))/Stride_w +1; theData_im =New float[channels*height*width]; -Data_col =New float[channels*output_h*output_w*kernel_h*Kernel_w]; in      the     //init input image Data the      for(intm=0; m<channels;++m) About     { the        for(intI=0; ii) the       { the          for(intj=0; j<width;++j) +         { -DATA_IM[M*WIDTH*HEIGHT+I*WIDTH+J] = m*width*height+ I*width +J; thecout <<data_im[m*width*height+i*width+j] <<' ';Bayi         } thecout <<Endl; the       } -     } -      the im2col_cpu (data_im, channels, the height,width, Kernel_h, Kernel_w, the Pad_h, Pad_w, the Stride_h, Stride_w, - Dilation_h, Dilation_w, the data_col); thecout <<channels<<Endl; thecout <<output_h<<Endl;94cout <<output_w<<Endl; thecout <<kernel_h<<Endl; thecout <<kernel_w<<Endl; thecout <<"Error"<<Endl;98      for(intI=0; i<kernel_w*kernel_h*channels;++i) About     {     -          for(intj=0; j<output_w*output_h;++j)101         {102cout <<data_col[i*output_w*output_h+j]<<' ';103         }104cout <<Endl; the     }106 107     return 0;108}

Multi-channel convolution image others have given a lot of, we can search for the basic is from a piece. Here is an understanding of my own process, and the output of the program is exactly the same

Analysis of the realization of Im2col in Caffe