[VC application] Read and Write BMP files

BMP file read/write

Skyseraph Mar 10th 2011 hqu

Email: zgzhaobo@gmail.com QQ: 452728574

Latest modified Date: Mar 10th 2011 hqu

Step 1: Include the header file and define global variables

# Include "windows. H" // contains bitmapfileheader, bitmapinfoheader, rgbquad, and other structural Definitions

Unsigned char * pbmpbuf; // pointer for reading image data
Int BMP width; // The image width.
Int bmpheight; // Image Height
Rgbquad * pcolortable; // color table pointer
Int bibitcount; // image type, number of digits per pixel

Step 2: Write a read/write function

Read operations

 /************************************ * *********************************** Function Name: readbmp () * function parameter: char * BMP name-file name and path * return value: 0 indicates failure, 1 indicates success * Description: an image file name and path are given, read the bitmap data, width, height, color table, and * bits per pixel into the memory, in the corresponding global variables ********************************* * ***********************************/bool readbmp (char * BMP name) {// open the specified image file * fp = fopen (BMP name, "rb") in binary read mode; If (FP = 0) return 0; // skip the bitmap file header structure bitmapfileheaderfseek (FP, sizeof (bitmapfileheader), 0); // define the bitmap information header structure variable and read the bitmap information header into the memory, in the variable head, bitmapinfoheader head; fread (& head, sizeof (bitmapinfoheader), 1, FP ); // obtain information such as image width, height, and the number of digits occupied by each pixel. BMP width = head. biwidth; bmpheight = head. biheight; bibitcount = head. bibitcount; // defines the variable to calculate the number of bytes occupied by pixels in each line of the image (must be a multiple of 4) int linebyte = (BMP width * bibitcount/8 + 3)/4*4; // grayscale images have a color table, and the color table items are 256if (bibitcount = 8) // apply for the space required by the color table, read the color table into memory {pcolortable = new rgbquad [256]; fread (pcolortable, sizeof (rgbquad), 256, FP);} // space required to apply for bitmap data, read bitmap data into memory pbmpbuf = new unsigned char [linebyte * bmpheight]; fread (pbmpbuf, 1, linebyte * bmpheight, FP); // close the file fclose (FP ); return 1 ;}

Write operation

/*************************************** * ** Function Name: savebmp () * function parameters: * char * BMP name-file name and path * unsigned char * imgbuf-bitmap data to be stored on the disk * int width-the width of the bitmap to be stored in pixels * int height-pixel unit: disk to be saved. The bitmap height is * int ititcount-the number of digits occupied by each pixel * rgbquad * pcolortable-color table pointer *. Return Value: 0 is a failure, 1 is a success ** Note: given an image bitmap data, width, height, color table pointer, and the number of digits occupied by each pixel, etc, * write it to the specified file ********************************* * ***********************************/bool savebmp (char * BMP name, unsigned char * I Mgbuf, int width, int height, int bibitcount, rgbquad * pcolortable) {// If the bitmap data pointer is 0, no data is passed in, and the function returns if (! Imgbuf) return 0; // color table size, in bytes. The gray image color table size is 1024 bytes, and the color image color table size is 0int colortablesize = 0; If (bibitcount = 8) colortablesize = 1024; // The number of bytes in each row of the image data to be stored is a multiple of 4. Int linebyte = (width * bibitcount/8 + 3)/4*4; // open the file * fp = fopen (BMP name, "WB") in binary mode; If (FP = 0) return 0; // apply for bitmap file header Structure Variables, fill in the file header information bitmapfileheader filehead; filehead. bftype = 0x4d42; // BMP Type // bfsize is the sum of the four components of the image file filehead. bfsize = sizeof (bitmapfileheader) + sizeof (bitmapinfoheader) + colortablesize + linebyte * height; filehead. bfreserved1 = 0; filehead. bfreserved2 = 0; // bfoffbits is the sum of the space required for the first three parts of the image file filehead. bfoffbits = 54 + colortablesize; // write the file header into the file fwrite (& filehead, sizeof (bitmapfileheader), 1, FP); // apply for bitmap information header Structure Variables, fill in the Information header information bitmapinfoheader head; head. bibitcount = bibitcount; head. biclrimportant = 0; head. biclrused = 0; head. bicompression = 0; head. biheight = height; head. biplanes = 1; head. bisize = 40; head. bisizeimage = linebyte * height; head. biwidth = width; head. bixpelspermeter = 0; head. biypelspermeter = 0; // write the bitmap information header into the memory fwrite (& head, sizeof (bitmapinfoheader), 1, FP); // If the grayscale image has a color table, write File if (bibitcount = 8) fwrite (pcolortable, sizeof (rgbquad), 256, FP); // write bitmap data into file fwrite (imgbuf, height * linebyte, 1, FP); // close the file fclose (FP); return 1 ;}

Step 3: Compile the main function

Test 1

 
Int main () {// read the specified BMP file into the memory char readpath [] = "lena.bmp"; readbmp (readpath ); // output image information printf ("width = % d, Height = % d, bibitcount = % d \ n", BMP width, bmpheight, bibitcount ); // Save the image data disk char writepath [] = "lenacpy1.bmp"; savebmp (writepath, pbmpbuf, BMP width, bmpheight, bibitcount, pcolortable); // clear the buffer, pbmpbuf and pcolortable are global variables. When a file is read, the requested space is Delete [] pbmpbuf; If (bibitcount = 8) Delete [] pcolortable; return 0 ;}
 

Test 2

Int main () {// read the specified BMP file into the memory char readpath [] = "lena.bmp"; readbmp (readpath ); // output image information printf ("width = % d, Height = % d, bibitcount = % d \ n", BMP width, bmpheight, bibitcount); // loop variable, the coordinate int I, j; // number of bytes in each row int linebyte = (BMP width * bibitcount/8 + 3)/4*4; // cyclic variable, for color images, traverse each pixel's three components int K; // set the first part of the image in the lower left corner to black if (bibitcount = 8) // for Grayscale Images {for (I = 0; I <bmpheight/2; I ++) {for (j = 0; j <BMP width/2; j ++) {* (pbmpbuf + I * linebyte + J) = 0 ;}} else if (bibitcount = 24) // color image {for (I = 0; I <bmpheight/2; I ++) {for (j = 0; j <BMP width/2; j ++) {for (k = 0; k <3; k ++) // each pixel RGB three components are set to 0 to black * (pbmpbuf + I * linebyte + J * 3 + k) = 0 ;}}} // Save the image data disk char writepath [] = "lenacpy2.bmp"; savebmp (writepath, pbmpbuf, BMP width, bmpheight, bibitcount, pcolortable); // clear the buffer, pbmpbuf and pcolortable are global variables. When a file is read, the requested space is Delete [] pbmpbuf; If (bibitcount = 8) Delete [] pcolortable; return 0;
 

Test 3

Int main () {// read the specified BMP file into the memory char readpath [] = "lena.bmp"; readbmp (readpath ); // output image information printf ("width = % d, Height = % d, bibitcount = % d \ n", BMP width, bmpheight, bibitcount ); // change the value of the blue component of the grayscale image. Check the changes before and after the image. If (bibitcount = 8) {for (INT I = 0; I <256; I ++) {pcolortable [I]. rgbblue = 255-pcolortable [I]. rgbblue ;}}// Save the image data disk char writepath [] = "lenacpy3.bmp"; savebmp (writepath, pbmpbuf, BMP width, bmpheight, bibitcount, pcolortable); // clear the buffer, pbmpbuf and pcolortable are global variables. When a file is read, the requested space is Delete [] pbmpbuf; If (bibitcount = 8) Delete [] pcolortable; return 0 ;}
 

Author: skyseraph

Email/Gtalk: zgzhaobo@gmail.com QQ: 452728574

From: http://www.cnblogs.com/skyseraph/

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