Create an RGBA image in C++ -

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i have matrix of 640x480x4 values, i.e. 640x480 pixels each 4 channels (rgba). want create png file shows transparency. have tried using opencv, apparently transparency not supported. quickest , easiest way can this, need save few images?

as other said, can't write png image file in c++ without using external library.

libpng smallest , portable solution, official png reference library , used of image library write , read png files. it's easy use c library may not best solution c++ novice.

exemple of writing png image libpng :

file *fp = fopen("file.png", "wb"); png_structp png_ptr = png_create_write_struct(png_libpng_ver_string, 0, 0, 0); png_infop info_ptr = png_create_info_struct(png_ptr); png_init_io(png_ptr, fp);  /* write header */ png_set_ihdr(png_ptr, info_ptr, width, height,     bit_depth, color_type, png_interlace_none,     png_compression_type_base, png_filter_type_base);  png_write_info(png_ptr, info_ptr);  /* write bytes */ png_bytep * row_pointers; <allocate row_pointers , store each row of image in it> png_write_image(png_ptr, row_pointers); png_write_end(png_ptr, null);  /* cleanup heap allocation */ (y=0; y<height; y++) free(row_pointers[y]); free(row_pointers);  fclose(fp);

as can see needs quite lines initialize writing context, , voluntarily removed error management bit tricky libpng (use of setjmp instance) , definitly not suitable novice c programmer.

you may take @ higher level image library such imagemagick has c++ api called magick++, here example of writing image in memory png file :

magick::blob blob(data, length);  magick::image image;  image.size("640x480")  image.magick("rgba");  image.read(blob); image.write("file.png");

as can see, it's easier higher level library.


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