png_transform.c

/*
 * Copyright 2002-2010 Guillaume Cottenceau.
 *
 * This software may be freely redistributed under the terms
 * of the X11 license.
 *
 */

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>

#include <png.h>

void
abort_(const char *s, ...)
{
	va_list args;
	va_start(args, s);
	vfprintf(stderr, s, args);
	fprintf(stderr, "\n");
	va_end(args);
	abort();
}

int x, y;

struct decoded_image {
	int         w, h;
	png_byte    color_type;
	png_byte    bit_depth;
	png_structp png_ptr;
	png_infop   info_ptr;
	png_infop   end_info;
	int         number_of_passes;
	png_bytep   *row_pointers;
};

void
read_png_file(char *file_name, struct decoded_image *img)
{
	char header[8];        // 8 is the maximum size that can be checked

	/* open file and test for it being a png */
	FILE *fp = fopen(file_name, "rb");
	if (!fp)
		abort_("[read_png_file] File %s could not be opened for reading", file_name);
	fread(header, 1, 8, fp);
	if (png_sig_cmp((png_const_bytep)header, 0, 8))
		abort_("[read_png_file] File %s is not recognized as a PNG file", file_name);


	/* initialize stuff */
	img->png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);

	if (!img->png_ptr)
		abort_("[read_png_file] png_create_read_struct failed");

	img->info_ptr = png_create_info_struct(img->png_ptr);
	if (!img->info_ptr)
		abort_("[read_png_file] png_create_info_struct failed");

	if (setjmp(png_jmpbuf(img->png_ptr)))
		abort_("[read_png_file] Error during init_io");


    png_init_io(img->png_ptr, fp);
    png_set_sig_bytes(img->png_ptr, 8);

    png_read_info(img->png_ptr, img->info_ptr);

    img->w      = png_get_image_width(img->png_ptr, img->info_ptr);
    img->h     = png_get_image_height(img->png_ptr, img->info_ptr);
    img->color_type = png_get_color_type(img->png_ptr, img->info_ptr);
    img->bit_depth  = png_get_bit_depth(img->png_ptr, img->info_ptr);

    img->number_of_passes = png_set_interlace_handling(img->png_ptr);
    png_read_update_info(img->png_ptr, img->info_ptr);


	/* read file */
	if (setjmp(png_jmpbuf(img->png_ptr)))
		abort_("[read_png_file] Error during read_image");

	img->row_pointers = (png_bytep*) malloc(sizeof(png_bytep) * img->h);
	for (y = 0; y < img->h; y++)
		img->row_pointers[y] = (png_byte*) malloc(png_get_rowbytes(img->png_ptr, img->info_ptr));

	png_read_image(img->png_ptr, img->row_pointers);
	fclose(fp);
printf("read is done \n");
}


static void
write_png_file(char *file_name, struct decoded_image *img)
{
 printf("Starting write_png_file\n");
  /* create file */
  FILE *fp = fopen(file_name, "wb");
  if (!fp)
    abort_("[write_png_file] File %s could not be opened for writing", file_name);


  /* initialize stuff */
  img->png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);

  if (!img->png_ptr)
    abort_("[write_png_file] png_create_write_struct failed");

  img->info_ptr = png_create_info_struct(img->png_ptr);
  if (!img->info_ptr)
    abort_("[write_png_file] png_create_info_struct failed");

  if (setjmp(png_jmpbuf(img->png_ptr)))
    abort_("[write_png_file] Error during init_io");

  png_init_io(img->png_ptr, fp);


	/* write header */
	if (setjmp(png_jmpbuf(img->png_ptr)))
		abort_("[write_png_file] Error during writing header");

	png_set_IHDR(img->png_ptr, img->info_ptr, img->w, img->h,
		img->bit_depth, img->color_type, PNG_INTERLACE_NONE,
		PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);

	png_write_info(img->png_ptr, img->info_ptr);


	/* write bytes */
	if (setjmp(png_jmpbuf(img->png_ptr)))
		abort_("[write_png_file] Error during writing bytes");

	png_write_image(img->png_ptr, img->row_pointers);


	/* end write */
	if (setjmp(png_jmpbuf(img->png_ptr)))
		abort_("[write_png_file] Error during end of write");

	png_write_end(img->png_ptr, NULL);

	/* cleanup heap allocation */
	for (y = 0; y < img->h; y++)
		free(img->row_pointers[y]);
	free(img->row_pointers);
	png_destroy_write_struct(&img->png_ptr, &img->info_ptr);

	fclose(fp);
	printf("End write_png_file\n");
}


static int
process_file(struct decoded_image *img)
{
	printf("Checking PNG format\n");	
	if (png_get_color_type(img->png_ptr, img->info_ptr) != PNG_COLOR_TYPE_RGBA)
	{
		printf("[process_file] color_type of input file must be PNG_COLOR_TYPE_RGBA (%d) (is %d)",PNG_COLOR_TYPE_RGBA, png_get_color_type(img->png_ptr, img->info_ptr));
		return 1;
	}

	printf("Starting processing\n");

        for (y=0; y< img->h; y++) {
                png_byte* row = img->row_pointers[y];
                for (x=0; x< img->w; x++) {
                        png_byte* ptr = &(row[x*4]);
                                                						
		/* set red value to 0 and green value to the blue one */
		  ptr[0] = 0;
                  ptr[1] = ptr[2];
		
                }
        }

	png_destroy_read_struct(&img->png_ptr, &img->info_ptr, NULL);
	printf("End processing\n");

	return 0;
}
static int transformation(struct decoded_image *img, float red,float green,float blue)
{
	
	printf("Checking PNG format\n");	
	if (png_get_color_type(img->png_ptr, img->info_ptr) != PNG_COLOR_TYPE_RGBA)
	{
		printf("[transformation] color_type of input file must be PNG_COLOR_TYPE_RGBA (%d) (is %d)",PNG_COLOR_TYPE_RGBA, png_get_color_type(img->png_ptr, img->info_ptr));
		return 1;
	}

	printf("Starting Transformation\n");

        for (y=0; y< img->h; y++) {
                png_byte* row = img->row_pointers[y];
                for (x=0; x< img->w; x++) {
                        png_byte* ptr = &(row[x*4]);
                                                						
		/*set weight 0.5 for red, 0.8 for green and 1 for blue */
		
                     	ptr[0] = red*ptr[0];
                        ptr[1] = green*ptr[1];
			ptr[2] = blue*ptr[2];

                }
        }

	png_destroy_read_struct(&img->png_ptr, &img->info_ptr, NULL);
	printf("End Transformation\n");


	return 0;
}



int
main(int argc, char **argv)
{

	/* variable to choise the transformation to apply*/
	int c;
	float red,green,blue;
	if (argc != 6)
		abort_("Usage: program_name <file_in> <file_out> <weight red> <weight green> <weight blue>");

	struct decoded_image *img = malloc(sizeof(struct decoded_image));
	if (!img)
    	abort_("[main] create struct decoded_image failed");

	
	printf("Which transformation do you want ? \n");
	printf("press 1 to set red value to 0 and green value to the blue one \n");
	printf("press 2 to set 0.5 for red, 0.8 for green and 1 for blue \n");

	scanf("%d",&c);
	printf("Reading input PNG\n");
	read_png_file(argv[1], &img);
	if(c==1)
	{
		process_file(&img);

		printf("Writing output PNG\n");
		write_png_file(argv[2], &img);
	}
	else
	if(c==2)
	{
		red=atof(argv[3]);
		green=atof(argv[4]);
		blue=atof(argv[5]);
		transformation(&img,red,green,blue);
		write_png_file(argv[2], &img);
	}
		
       printf("END\n");

	return 0;
}