[英]scale pixels of an image using opencv library and c++
我正在尝试使用OpenCV 2.4.5和Visual Studio 2010 Express创建简单的一维条形码阅读器。
到目前为止,这是我的代码:
//define Image path:
char* imageName = "D:\\Barcode Reader\\test3.jpg";
cv::Mat src = cv::imread(imageName);
if( !src.data )
{ return -1; }
//convert image to grayscale img:
cv::Mat gray_image;
cvtColor (src, gray_image, CV_BGR2GRAY);
unsigned char color;
unsigned char next_black_color = 0;
unsigned char next_white_color = 0;
int buffer[500];
float factor = (float)gray_image.cols / (float)required_width;
//start to search for pixels from left to right (in the middle of the img):
unsigned char *position = gray_image.ptr(gray_image.rows/2,0);
//iterate through the whole image length:
for (int col = 1; col <= gray_image.cols; col++)
{
//...and store the pixel value in color variable for possible output (which would be like 0-127 for black colors and 127-255 for white colors:
color = *position;
position++;
//check the pixel value ( < 127 everything bellow has dark color):
if (color < 127)
{
//...and after each position checked, go to next pixel and save the number of occurences of black pixels:
next_black_color++;
buffer[col] = next_black_color;
std::cout << col << ": " << buffer[col] << " ";
}
else
{
//set the counter variable to null for the next occurence of black pixel:
next_black_color = 0;
}
//the same goes for white pixels:
if (color > 127)
{
next_white_color++;
buffer[col] = next_white_color;
std::cout << col << ": " << buffer[col] << " ";
}
else
{
next_white_color = 0;
}
}
//show the results:
std::cout<<" Number of pixels in width = " << src.cols << std::endl <<
"Number of pixels in height = " << src.rows << std::endl;
cv::imshow("Normal Image", src);
cv::imshow("Gray Image", gray_image);
cv::waitKey(0);
return 0;
测试图像是具有以下顺序的黑白像素的100x100px图像(为更好地理解,将其描述为二进制代码:1 = black,0 = white)10100 <.. white pixels ..> 00101
我这样做的原因很简单...
假设我有一个UPC条形码,可以长81个像素。 但是,我加载的图像的长度超过1000像素。
为了应用检测并将我的加载图像与UPC模式进行比较,我必须先缩放加载图像以正确校正像素值。 (我使用“比例”一词...因为如果我只是“调整”图像的大小...它将切断919个像素,因此无法进行检测。)
我知道加载的图像是UPC模式的12,34倍(接近12)....我现在不在乎正确的值...我所关心的只是当前的实现... )
使用此实现,我面临以下问题:
这些事件将存储如下:
____[Array]____
Position | Occurence
1 ......... 1 (First position with first black pixel)
2 ......... 1 (white)
3 ......... 1 (black)
4 ......... 1 (white pixels until next black pixel appears..)
5 ......... 2 (___Problem here!___ ... should be 94!)
6 ......... 3 .
. ......... . .
100 ....... 100(end)
但是应该是:
____[Array]____
Position | Occurence
1 ......... 1 (First position with first black pixel)
2 ......... 1 (white)
3 ......... 1 (black)
4 ......... 94 (count all white pixels until black appears again)
5 ......... 1 (black)
6 ......... 1 (white)
7 ......... 1 (black) -> end
我希望我能提供足够的信息来解答。
请帮助我改正我的代码。 最好的问候Ondrej
我认为您应该重做周期。 是正确的,但是太复杂了。 您的代码存在以下问题:
buffer[col] = next_black_color;
变量col始终在增加,因此将更新的颜色计数添加到阵列中的新插槽。 在示例中,位置5不能有97,因为给定代码在位置5,您只能处理5个像素。
您的代码的另一个小问题是,您有两个互斥条件。 如果color <127并且color>127。首先,如果color <127,则else表示颜色> = 127。 等号很重要! 如果所有颜色均为127,则您的代码将失败。
以下是该算法的草稿:
int arr[] = {0,0,180,180,180,180,180,180,180,180,180,0,0,0};
int size = 14;
bool last_dark = false;
bool current_dark = false;
if(arr[0] < 127){
last_dark = true;
}
int counter = 0;
for(int i = 0; i < size; i++){
if(arr[i] < 127){
current_dark = true;
} else {
current_dark = false;
}
// is current pixel same shade as last?
if(last_dark == current_dark){
counter++;
} else {
cout << counter << endl;
counter = 1; // the last color is already processed
}
last_dark = current_dark;
}
// following line is important to get the last count
cout << counter << endl;
绝不是完整的。 您将必须适应您的需求。 在最后一个if中,我们不能直接比较last和current的值,因为120和12都是暗的,但不是相同的值。 在您的代码中,将cout替换为正确的向量分配,不要忘了循环之外的那个。 ;)
问候,
jnovacho
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