How to Change Hue Level of an Image in Qt

Qt offers convenient classes for basic image processing and pixel manipulation. In this article I am going to describe how you can change the hue level of a whole image using QImage class in Qt.

It’s quite simple as long as you know what hue is. So to start, let’s look at the following images:

All of these images have the same components in the HSV Color Space except their Hue value.

Below is how you can modify the Hue element of a whole image (QImage) in Qt:

for(int i=0; i<image.width(); i++)
for(int j=0; j<image.height(); j++)
QColor color = image.pixelColor(i,j);

int hue = color.hue();

// modify hue as you’d like and write back to the image
color.setHsv(hue, color.saturation(), color.value(), color.alpha());
image.setPixelColor(i, j, color);

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