i.MX ProcessorsのトピックOV5460 Camera image quality

OV5460 Camera image quality

renejansen — Mon, 06 Nov 2017 15:03:01 GMT

We are using the MIPI-CSI camera interface of the iMX7 processor to retrieve an image of an OV5640 based camera.The purpose of this camera image is read a barcode from the image.

Before developing our own hardware, we tested a OV5640 base webcam on a linux (ubuntu) machine to check the image quality. The quality was high enough to be able to read barcodes that were visible as a single pixel for each bar. The images were sharp, even at short ranges, although the autofocus could take some time before stabilizing.

Now we have developed are own board, thats a copy of the iMX7 sabre board with regard to the MPIP-CSI interface. When using the mipi-csi camera, the image quality is very bad: even at low image reolutions, the lines in the image are blurred, see the attached image. This limits to barcodes to be processed very much.

We tried to improve the autofocus by increasing the image distance and improve the lighting conditions, but no improvement seemed possible.

We also tried to improve the image quality by changing resolution, but it seems as if the blurriness is independant of the resolution. We also tested a few different camera modules

It might be that the algorithme to convert the UYV pixels to a (black and white) bitmap is incorrect. Are there ways to test the camera image output, for instance on the iMX7 Sabre development board? Is there software available to take a snapshot of the camera output? Have other developers succesfully used the camera in their applications?

Re: OV5460 Camera image quality

gusarambula — Wed, 15 Nov 2017 18:27:45 GMT

Hello Rene Jansen,

There are not many other threads pertaining the usage of the OV5460 with the i.MX7D, but there are some regarding similar cameras. (You may find a lot of threads for the OV5640)

Have you tried using gstreamer to encode to a file or to take a snapshot? I haven’t tested it but perhaps that may be of help. The command would look somewhat like this:

gst-launch mfw_v4lsrc num-buffers=1 capture-mode=1 ! jpegenc ! filesink location=output.jpg

Regards,

Re: OV5460 Camera image quality

ArgirisDiamandi — Fri, 17 Nov 2017 08:04:23 GMT

Rene,

You will need to provide more information to get any helpful feedback.

Are you testing on the same camera module (USB?) as your first tests, but you have integrated a different module on your design?

Are you aware that the sensor can handle the autofocus only when there is hardware to move the lens (e.g. voice coil) and firmware on the sensor MCU to execute the autofocus?

I suggest you gather more information on the sensor itself from the sensor manufacturer and documentation on the camera module from the module manufacturer you have used.