same jpeg image decode incorrect

[stanley0614]

I am a new in using stb_image. I load a jpeg picture to opengl texture by using stb_image. and I find the picture not correct. but when I use ImageMagick to load the picture it is good! I do not know why, Is this a bug in stb_image or this kind of jpeg is not supported ? anyone can help me, Thank you very much.
original image:

stb_image load to texture:

[zao]

TL;DR - probably user application error.

The image as presented here round-trips correctly through stbi_load -> stbi_write_png for me with the following test program:

#define STB_IMAGE_IMPLEMENTATION 1
#define STB_IMAGE_WRITE_IMPLEMENTATION 1
#include "stb_image.h"
#include "stb_image_write.h"

#define IN_FILENAME "/mnt/y/Downloads/51249360-fcb19f80-19cd-11e9-86eb-787bb44422ac.jpeg"
#define OUT_FILENAME "/mnt/f/Temp/car.png"

int main() {
        int x, y, n;
        unsigned char* data = stbi_load(IN_FILENAME, &x, &y, &n, 0);
        fprintf(stderr, "x: %d, y: %d, n: %d\n", x, y, n);
        stbi_write_png(OUT_FILENAME, x, y, n, data, 0);
        free(data);
        return 0;
}

My psychic debugging hat tells me that you are uploading the image to OpenGL without setting GL_UNPACK_ALIGNMENT to 1. The default is 4, which means that whenever you upload pixel data to OpenGL, it'll pad out it's expectation of row stride to a round four bytes. As a row of your image is 529 * 3 (1587) bytes which is not divisible by four, you're losing one byte per row, resulting in the sloped weirdness you observe, with a region of undefined memory up top.

[stanley0614]

@zao Thank you very much. It is GL_UNPACK_ALIGNMENT reason. 再次感谢你！