问题描述
因此,我正在使用QT为我的班级进行图像操作分配,要求我将当前拥有的图像数据手动保存为PPM格式,并将其重新加载到QDialog程序中。
我设法正确保存了图像(使用gimp验证了输出文件),但是从文件中加载却造成了如下灾难
以下是原图:
负载不好:
//... opens the file and pulling out headers & etc...
unsigned char* data = new unsigned char[width*height*3];
//Manual loading each byte into char array
for(long h = 0; h < height; h++){ //for all 600 rows
getline(readPPM,temp); //readPPM is an ifstream,temp is a string
std::stringstream oneLine(temp);
for(long w = 0; w < width*3; w++){ //to every position in that line 800*3
int readVal;
oneLine >> readVal; //string stream autofill get the int value instead of just one number
data[width*h+w] = (unsigned char)readVal; //put it into unsign char
}
}
//Method 1: create the QImage with constructor
(it blacked out 2/3 of the bottom of the image,and I'm not exactly familiar with QImage data type)
imageData = QImage(data,width,height,QImage::Format_BGR888);
//Method 2: manually setting each pixel
for(int h = 0; h < height; h++){
for(int w = 0; w < width; w++){
int r,g,b;
r = (int)data[width*h+w*3];
g = (int)data[width*h+w*3+1];
b = (int)data[width*h+w*3+2];
QColor color = qRgb(r,b);
imageData.setPixelColor(w,h,color);
}
}
//...set image to display...
当我从文件中加载时,我希望显示器看起来像原始图像,并且不确定导致损坏的问题是什么,请帮忙
解决方法
一行图像的大小为3 * width
个字节,而不是width
个字节,因此应在data[]
索引中的任何位置修复。
即代码
data[width*h+w] = (unsigned char)readVal;
应替换为
data[3*width*h+w] = (unsigned char)readVal;
和代码
r = (int)data[width*h+w*3];
g = (int)data[width*h+w*3+1];
b = (int)data[width*h+w*3+2];
替换为
r = (int)data[3*width*h+w*3];
g = (int)data[3*width*h+w*3+1];
b = (int)data[3*width*h+w*3+2];