Question

Objective:

I am trying to use openCV function cvResize() to resample a 2D array.[I have a working code in opencv using cvResize, I know its usage] But the input 2D array which I want to resample is not any image read by openCV using cvLoadImage() instead –

1.I would want to read the 2D array from a text file I have. That file has floating point values, in it. I would open that file in this test code using opencv library, read the values in a 2D array of float.

2.Then use cvResize() to resize it. First I want to downsample it – width/2, height/2.

3.Then I want to upsample it by 4 – width*4, height*4. This is my final 2D array.

4.Store this final 2D array to a text file as floating point values.

5.Basically I want to use the Bilinear interpolation logic used by OpenCV, but on my own data. What path/which file can I see the code for cvResize()?

Any pointers appreciated.

Answer 1

The difficulty here seems to be that you are using a data type (2D array) to store the data read from the file, that is not compatible with what cvResize() works with (it’s IplImage* remember?).

If you are using the C interface of OpenCV (and by watching your other questions I know you are), after successfully reading the data from the file to your custom data type (2D array?) you need to create a IplImage* that is big enough to store this information.

IplImage* cv_data_img = cvCreateImage(cvSize(custom_data_height, custom_data_width), IPL_DEPTH_32F, 1);

and after that, you’ll have to iterate on cv_data_img copying the original data.

Once cv_data_img it’s filled with the data, you can create the others IplImage* you’ll need to store the result of cvResize().

At the end, you can iterate on the resulting IplImage* and copy it back to your original data type (2D array) or do whatever you want with it.