I want the resolution of the capture file to be different from the resolution of the preview.

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Hi. I am South Korea Student. I'm sorry I did not speak English well. I want the resolution of the capture file to be different from the resolution of the preview. I am using raspberry pi 3 b+ and usb camera, opencv, python. I want capture file resolution (1024, 768) but my LCD resolution (320, 240). The resolution of the preview image on my LCD is (320,240) and when the capture is done, the resolution of the capture file should be saved as (1024, 768). Is this possible? What if I can?

Thank you for reading.