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问题:
Yes i have been through the other questions that are related to this, but i found them not much help. They were some help but i am still a bit confused. So here what what i need to do:
We have a 132x65 screen. I have a 132x65 .bmp. I want to go through the .bmp and separate it into little 1x8 columns to get the binary of that 32-bit column. Then do that 132 times across, and do that 9 times down. Anything that is not white should be counted as a bit. example:
If the top left pixel of the picture is any color that is not white and the 7 pixels below that are white then that would be the first element of the array, the hex of that number, so the array would look like this: array [] = { 0x01 } and then it would continue to fill through those 132 columns and then do it again for 9 "sections" of rows. And the file result would be ONLY that array in a separate file.
I understand the header format for this, i have read the wiki article on .bmp file formats, my main problem is i don't really know how to interact with the .bmp when i actually want it to go inside and interact with each pixel from the image. I really dont need the whole thing, but maybe just an example of grabbing each pixel from the .bmp and outputting the color of the pixel into a file or something. My c++ is a little rusty (been doing java and javscript lately).
回答1:
If you want to read a known format BMP and don't care about how it's done (ie, internal-only thing) you can just take the BMP, ignore the header and use it as a pixel array. It is stored line by line starting at the bottom left. There are some detail snags for how it's packed but in my experience if you take a 32bpp image it can be completely ignored.
As a really simple example:
unsigned int *buffer; void readfile() { FILE *f = fopen("file.bmp", "rb"); buffer = new unsigned int[132*65]; fseek(f, 54); fread(buffer, 132*65*4, 1, f); fclose(f); } unsigned int getpixel(int x, int y) { //assuming your x/y starts from top left, like I usually do return buffer[(64 - y) * 132 + x]; }
回答2:
I had the same problem, but by reading BMP file format description I wrote a function that reads a .BMP file and stores it into a array. Maybe this function can help you:
unsigned int PIC::BinToNum(char *b,int bytes) { unsigned int tmpx = 0; unsigned int pw = 1; for(int i=0;i<bytes;i++) { tmpx += ((unsigned char)b[i]* pw); pw = pw * 256; } return tmpx; } int PIC::Open(const char *path) { int pad = 0; unsigned int sof = 0; unsigned int tx = 0; char tmp[4] = {0,0,0,0}; fstream file; file.open(path,ios::in); if(file.fail()) { width=height=ColorBits=size=0; return -1; } else { file.seekg(0,ios::beg); file.read(tmp,2); if(!(tmp[0] == 66 && tmp[1] == 77)) { width=height=ColorBits=size=0; return 0; } else { file.seekg(2,ios::beg); // 0x2 size file.read(tmp,4); size = BinToNum(tmp,4); file.seekg(18,ios::beg); // 0x12 width file.read(tmp,4); width = BinToNum(tmp,4); file.seekg(22,ios::beg); // 0x16 height file.read(tmp,4); height = BinToNum(tmp,4); file.seekg(28,ios::beg); // 0x1C Bits per Pixel file.read(tmp,2); ColorBits = BinToNum(tmp,2); file.seekg(10,ios::beg); // 0x0A start offset file.read(tmp,4); sof=BinToNum(tmp,4); file.seekg(34,ios::beg); // 0x22 Padding file.read(tmp,4); pad = BinToNum(tmp,4); pad = (int)(pad / height); // Compute Spacing in each row pad = pad - (width*ColorBits/8); // Initialize Matrix// matrix = new(unsigned int[height*width]); for(int h=height-1;h>=0;h--) { for(int w=0;w<=width-1;w++) { file.seekg(sof,ios::beg); file.read(tmp,(int)(ColorBits/8)); tx = BinToNum(tmp,(int)(ColorBits/8)); matrix[(h*width)+w] = tx; sof+=(int)(ColorBits/8); } sof +=pad; } } } file.close(); return 1; } Note:This functions is member of a class that i named it "PIC"...
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