What is the advantage of a 3MP OV3660 sensor on the ESP32 M5Stack camera if it can only save upto 2MP images? I am making a self-contained stills camera and the ESP32-based modules seem well-suited to my project due to the easy incorporation of a TFT viewfinder screen and TF card slot in one package. I am not interested in saving video or web streaming.
I have worked with the TTGO ESP32 camera that uses the OV2640 2MP sensor and can save full 2MP UXGA (1600x1200) resolution stills (albeit with mandatory JPEG compression turned on - I have only managed to get 1.3 MP images without compression).
I see now there is a version of ESP32 camera that uses the OV3660 3MP sensor (called 'M5Stack Timer Camera'). However, the specs for that camera https://docs.m5stack.com/#/en/unit/timercam say it can save upto a maximum of UXGA - i.e. 2MP images.
So what is the advantage of having a 3MP sensor chip if you can only save 2 MP images? Or is there a way of saving the full 3MP sensor resolution (i.e. 2048 x 1536) stills from this camera?
Thanks
The limit isn't the camera - it's the memory.
At 3 megapixels you have 3145728 pixels. At 3 bytes per pixel (8 bits each of red green and blue) it requires 9437184 bytes to store the image. That's more than can fit into the 8MB PSRAM.
1600x1200 will probably be one of the standard resolutions that the specific camera in use can capture, and is probably the biggest size that is below 8MB in size for a single frame.
So, what advantage of having a 3 megapixel camera? Well, none to you, other than the cost. It's probably cheaper to use a newer 3 megapixel camera than an older 2 megapixel camera.

It is perfectly possible to run at the resolutions you desire though. This resolution is known as QXGA and is supported by the OV3660 driver in the ESP32 Camera library.  There are some caveats though:

You must use JPEG compression. Not only is this to make the image small enough to fit into PSRAM but also to make it possible to write the whole frame into PSRAM fast enough that you don't miss bits of the data.
You will not be able to &quot;do&quot; anything with the image other than send it to somewhere else (such as an SD card or a web server). There just isn't enough room to uncompress the image.