how can i read jpg format images (or) pixel values
how can i read jpg format images (or) pixel values
First of all, let's assume that you're not using TurboC as your compiler.
That being the case, the easiest way to read a JPG file into a format where you can read pixels is to use a library.
libjpeg - Wikipedia
Yes, you can use fopen() to open the file, and fread() to read the whole file into memory.
But extracting pixels from the binary data involves a LOT of work, and a LOT of very serious maths.
If you want reasonable results in anything less than 6 months, then use a library.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
Here's code for loading JPEGs and all the other popular file formats for good measure.
GitHub - MalcolmMcLean/babyxrc: Resource compiler, packages images, fonts, cursors, etc as compilable C source. Portable ANSI C.
I'm the author of MiniBasic: How to write a script interpreter and Basic Algorithms
Visit my website for lots of associated C programming resources.
https://github.com/MalcolmMcLean
stb_image makes reading images quite painless. It's just a single header file you include in your own code, and that's it. Also it's a public domain license.
Here's a dumb example of reading the first 10 pixels of a JPG file...
Code:#include <stdio.h> #define STB_IMAGE_IMPLEMENTATION #include "stb_image.h" const size_t NUM_PIXELS_TO_PRINT = 10U; int main(void) { int width, height, comp; unsigned char *data = stbi_load("image.jpg", &width, &height, &comp, 0); if (data) { printf("width = %d, height = %d, comp = %d (channels)\n", width, height, comp); for (size_t i = 0; i < NUM_PIXELS_TO_PRINT * comp; i++) { printf("%02x%s", data[i], ((i + 1) % comp) ? "" : "\n"); } printf("\n"); } return 0; }
