使用libtiff在C中读取.tif图像会返回一列

时间:2018-12-31 22:06:33

标签: c libtiff

我想使用“ libtiff”库从“ .tiff”图像中读取u8位像素强度值。我遇到了此代码,并对其进行了修改,以根据需要读取8位值,并且仅返回一列的正确值。

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include "tiffio.h"
#define imsize 286628
 int count;
 int count2;
 uint8* im;
 uint32 imagelength;
 uint32 width;
int main(){

im = (uint8*)malloc(imsize*sizeof(uint8));
TIFF* tif = TIFFOpen("image1.tif", "r");
    if (tif) {

        tsize_t scanline;
        tdata_t buf;
        uint32 row;
        uint32 col;


        uint16 nsamples;

        TIFFGetField(tif, TIFFTAG_SAMPLESPERPIXEL, &nsamples);
        TIFFGetField(tif, TIFFTAG_IMAGELENGTH, &imagelength);
        TIFFGetField(tif,TIFFTAG_IMAGEWIDTH,&width);

        scanline = TIFFScanlineSize(tif);
        buf = _TIFFmalloc(scanline);
        uint8* data;

        for (row = 0; row < imagelength; row++)
        {
            TIFFReadScanline(tif, buf, row,1);
            count2++;
            for (col = 0; col < scanline; col++)
                data = (uint8*)buf;
                //printf("%d\n",col); remains the same not incrementing
                printf("%d ", *data);//printing for testing need only to copy to an array to access by index
                im[count] = *data;
                count++;
            printf("\n");

        }
        printf("im[1]= %d\n im[2] = %d \n im[3] = %d \n im[286628] = %d\n",im[0],im[1],im[2],im[286627]);
        _TIFFfree(buf);
        TIFFClose(tif);
        free(im);
    }
    printf("num of cols= %d\n",count);
    printf("num of rows = %d\n",count2);//both counts print col size
    printf("width = %d\n",width); //prints row size

    return 0;

}

在嵌套的forloop中,如果添加方括号,则循环将迭代正确的像素数 (对于本示例来说,#of-pixels = 286628,547x524图像),但是值不正确。 如果我将括号移开,我会得到正确的值,但第一列(只有547个值)。

需要进行哪些更改才能正确遍历所有像素?

注释: 我正在尝试获取矩阵值为“ imread()”的矩阵

1 个答案:

答案 0 :(得分:0)

col循环中,每一列都使用data = (uint8*)buf;做完全相同的事情,而{似乎是 first 列的数据。循环也缺少}大括号data = (uint8*)buf;

移动行

for (row = 0; row < imagelength; row++)
{
    TIFFReadScanline(tif, buf, row,1);
    count2++;
    data = (uint8*)buf;                     // move up
    for (col = 0; col < scanline; col++)
    {                                       // add braces
        printf("%d ", *data);
        im[count] = *data;
        count++;
        data++;                             // increment buffer pointer
    }
    printf("\n");
}

在列循环外并在循环内递增。

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