从摄像头采集JPEG数据并转换成zbar能扫描的灰度数据,4个缓冲区,不使用opencv , 使用jpeglib库实现程序
时间: 2024-02-23 17:00:42 浏览: 29
好的,这个问题需要分步骤来实现。
1. 首先,需要使用jpeglib库来读取JPEG数据。这可以通过以下代码来实现:
```c
#include <stdio.h>
#include <jpeglib.h>
struct my_error_mgr {
struct jpeg_error_mgr pub;
jmp_buf setjmp_buffer;
};
typedef struct my_error_mgr * my_error_ptr;
METHODDEF(void)
my_error_exit (j_common_ptr cinfo)
{
my_error_ptr myerr = (my_error_ptr) cinfo->err;
(*cinfo->err->output_message) (cinfo);
longjmp(myerr->setjmp_buffer, 1);
}
int read_jpeg_file(const char *filename, unsigned char **out_data, int *out_width, int *out_height) {
FILE *infile;
struct jpeg_decompress_struct cinfo;
struct my_error_mgr jerr;
JSAMPROW row_pointer[1];
int row_stride;
if ((infile = fopen(filename, "rb")) == NULL) {
fprintf(stderr, "Can't open %s\n", filename);
return 0;
}
cinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = my_error_exit;
if (setjmp(jerr.setjmp_buffer)) {
jpeg_destroy_decompress(&cinfo);
fclose(infile);
return 0;
}
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, infile);
jpeg_read_header(&cinfo, TRUE);
jpeg_start_decompress(&cinfo);
*out_width = cinfo.output_width;
*out_height = cinfo.output_height;
int num_channels = cinfo.output_components;
int row_size = *out_width * num_channels;
*out_data = (unsigned char*)malloc(row_size * (*out_height)); // Allocate memory for the output data.
row_stride = cinfo.output_width * cinfo.output_components;
while (cinfo.output_scanline < cinfo.output_height) {
row_pointer[0] = &((*out_data)[cinfo.output_scanline * row_stride]);
jpeg_read_scanlines(&cinfo, row_pointer, 1);
}
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
fclose(infile);
return 1;
}
```
这个函数将读取指定的JPEG文件,并将其解压缩为RGB数据。它还将返回图像的宽度和高度。
2. 接下来,需要将RGB数据转换为灰度数据。这可以通过以下代码来实现:
```c
void rgb_to_gray(unsigned char *in_data, int in_width, int in_height, unsigned char *out_data) {
int num_pixels = in_width * in_height;
for (int i = 0; i < num_pixels; i++) {
int r = in_data[i * 3];
int g = in_data[i * 3 + 1];
int b = in_data[i * 3 + 2];
out_data[i] = 0.2989 * r + 0.5870 * g + 0.1140 * b; // Convert to grayscale.
}
}
```
这个函数将输入的RGB数据转换为灰度数据,并将其存储在输出数据数组中。
3. 最后,需要将灰度数据传递给zbar库进行扫描。这可以通过以下代码来实现:
```c
#include <zbar.h>
void scan_qr_code(unsigned char *data, int width, int height) {
zbar_image_scanner_t *scanner = zbar_image_scanner_create();
zbar_image_t *image = zbar_image_create();
zbar_image_set_format(image, zbar_fourcc('G', 'R', 'E', 'Y'));
zbar_image_set_size(image, width, height);
zbar_image_set_data(image, data, width * height, NULL);
int result = zbar_scan_image(scanner, image);
if (result > 0) {
const zbar_symbol_t *symbol = zbar_image_first_symbol(image);
for (; symbol; symbol = zbar_symbol_next(symbol)) {
const char *symbol_data = zbar_symbol_get_data(symbol);
printf("Scanned QR code: %s\n", symbol_data);
}
}
zbar_image_destroy(image);
zbar_image_scanner_destroy(scanner);
}
```
这个函数将输入的灰度数据传递给zbar库进行扫描,并在找到QR码时输出其数据。
将这些函数结合起来,可以实现从摄像头采集JPEG数据并转换为zbar能够扫描的灰度数据的程序。
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