OpenGL image viewer, need some help on implementation

[Randulf]

Is there a specific reason why you're doing it with OpenGL?

Not really. Main reason is that I have used OpenGL before but for 3D.
Is QPainter easier to use?

[wysota]

I think you'd have fewer problems with a painter approach. All the rendering problems (transformations, etc.) would vanish and getting cursor coordinates would be as easy as reading a variable from the mouse event.

The most basic way to implement the viewer would be to use a QLabel with a pixmap. You can also embed it into a scroll area if you want scroll bars. Of course you can draw the image yourself using QPainter if you want more control over it (like easy scaling, etc.).

[minimoog]

We talk about HDR images, which pixel is represented with 16 bit float, 32 bit float or 32 bit integer. QPixmap doesn't support this kind of format. OpenGL support textures in 32 bit float format (GF 6 up, Radeon 9800 up) or 16 bit float (GF2 up). Also, he can use shaders for image processing.

[wysota]

We talk about HDR images, which pixel is represented with 16 bit float, 32 bit float or 32 bit integer. QPixmap doesn't support this kind of format.

Does your screen support it? Because if not, there is no point in doing something which you'll never see.

Also, he can use shaders for image processing.

And probe texels for colours when he wants to check the pixel value?

Using shaders would make sense if he had 100 images per second to process, but not with an image viewer. At least that's my point of view.