問題描述
我有一個 QImage，我需要將它轉(zhuǎn)換為灰度，然后再用顏色繪制它.我發(fā)現(xiàn)了一個 allGray() 和 isGrayScale() 函數(shù)來檢查圖像是否已經(jīng)是灰度的，但沒有 toGrayScale() 或類似名稱功能.
I have a QImage and I need to convert it to grayscale, then later paint over that with colors. I found an allGray() and isGrayScale() function to check if an image is already grayscale, but no toGrayScale() or similarly-named function.
現(xiàn)在我正在使用這段代碼，但它的性能不是很好:
Right now I'm using this code, but it's does not have a very good performance:
for (int ii = 0; ii < image.width(); ii++) {
for (int jj = 0; jj < image.height(); jj++) {
int gray = qGray(image.pixel(ii, jj));
image.setPixel(ii, jj, QColor(gray, gray, gray).rgb());
}
}
在性能方面，將 QImage 轉(zhuǎn)換為灰度的最佳方法是什么?
What would be the best way, performance-wise, to convert a QImage to grayscale?
推薦答案
從 Qt 5.5 開始，您可以調(diào)用 QImage::convertToFormat() 將 QImage 轉(zhuǎn)換為灰度，如下所示:
Since Qt 5.5, you can call QImage::convertToFormat() to convert a QImage to grayscale as follows:
QImage image = ...;
image.convertToFormat(QImage::Format_Grayscale8);
這篇關(guān)于將 QImage 轉(zhuǎn)換為灰度的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！