Important: Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct
Convert and resize matrix to image
Ankit.Jain last edited by
I am currently have a requirement to display data from a database (signal strength) as a heatmap. The problem I am facing is that the data is too sparse [it's uniformly distributed over a 2D space though].
On plotting the data as blocks, the image comes out as having jagged edges. I tried blurring out the edges [I failed miserably], I tried increasing my corpus by averaging the data [there was something wrong with my approach as the result still had some blocky-ness].
I was suggested to make a small image and resize it with some interpolation[Cubic and Sal] technique.
I think I should be able to manage making the db data into an image using :
The problem comes for interpolation while resizing. I didn't find anything which would allow me to do the same as a library. I was wondering if I missed something or if there could be any other way for getting a good result. A link to any example which could give me a lead would be highly appreciated.
Can you show the source image ?
Im wondering if some gaussian blur would make it look better.
Its easy to test with photoshop if you can provide a test image. ( blocky one)
If not possible you could test with something like
Ankit.Jain last edited by Ankit.Jain
@mrjj Sorry for not mentioning this before, I already tried a Gaussian Blur, it didn't help.
The data is have is in the form: (xCood, yCood, zCood, value)
For the first phase I am ignoring zCood.
The problem comes with the sample data granuality as data is something like:
I have a canvas of 1500x1500
The image before gaussian (The border is part of a layer above the image, so they aren't going anywhere soon):
After Gaussian Blurring (and some some interpolation on my part)(the data is a little different in both cases and I have done this in a separate application):
As you can see, the output still has some boxiness to it. Also, doing it like this is just removing the sharpness of the image [it is eventually meant to be used to visualize input data not be a sunset image. Not to mention I am going too far with the blurring here making it really heavy for a repaint].
Forgot to mention, I am using a continuous hue change here w.r.t value. But it seems that the proposal is for limited number of colors making the output even more blocky and blurring even more useless.
I eventually used the 2D shader for openGL.
Seems the most promising one yet