如何在Qt中输出这个24位图像

问题描述

我有一个unsigned字符数组，定义如下：

I have an unsigned char array that is defined like so:

unsigned char **chars = new unsigned char *[H];
for(int i = 0; i < H; i++)
{

    chars[i] = new unsigned char[W*3];
}

其中H是图像的高度，W是宽度，字符填充在该函数的其余部分，循环在输入图像的行x列。 Chars是按照红绿蓝的顺序填充的

Where H is the height of the image, and W is the width, and chars is populated in the rest of that function looping over rows x columns of the input image. Chars is populated in the order Red Green Blue

我想用这样的读取：

QImage *qi = new QImage(imwidth, imheight, QImage::Format_RGB888);
    for (int i = 0 ; i < imheight ; i++)
        for (int j = 0 ; j < imwidth ; j++)
        {      //not sure why, but have to flip j and i in the index for setPixel
               qi->setPixel(j,i,qRgb(imageData[i][j],imageData[i][j+1],imageData[i][j+2]));
               j+=3;

           }

   QPixmap p(QPixmap::fromImage(*qi,Qt::AutoColor));
   QPixmap p1(p.scaled(ui->menuBar->width(),ui->menuBar->width(), Qt::KeepAspectRatio, Qt::SmoothTransformation ));
   ui->viewLabel->setPixmap(p1);
   ui->viewLabel->setFixedHeight(p1.height());
   ui->viewLabel->setFixedWidth(p1.width());

其中chars返回到imageData数组中的此调用函数。

where chars was returned to this calling function in the imageData array.

我做错了什么？我应该使用不同的格式，即使我明确分配3个unsigned chars每个像素（这就是为什么我选择RGB888格式）。

What am I doing wrong? Should I use a different format, even though I am clearly allocating 3 unsigned chars per pixel (which is why I chose the RGB888 format). This code as posted returns an image, but it is displaying incorrectly - partially scrambled, washed out, etc

感谢

推荐答案

您可以创建，而不复制每个像素。

You can create a QImage directly from a block of data without copying every pixel.

由于您的图片是以不同的列储存，您需要像

Since your image is stored with separate rows, you need something like

QImage image = new QImage(width,height,QImage::RGB888)

for (int h=0;h<height;h++) {
    // scanLine returns a ptr to the start of the data for that row
    memcpy(image.scanLine(h),chars[h],width*3);
}

如果您使用RGB32，则需要手动设置每个像素的Alpha通道到0xff - 只是memset（）将整个数据0xff开头

if you use RGB32 then you need to manually set the alpha channel for each pixel to 0xff - just memset() the entire data to 0xff first

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