Strange noisy lines on QQQVGA images

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want2bfree
Posts: 2
Joined: Wed Dec 26, 2018 8:42 pm

Strange noisy lines on QQQVGA images

Postby want2bfree » Wed Dec 26, 2018 9:08 pm

Hi guys,

I've found that there appear strange noisy lines if I take images using frame sizes of QQQVGA and QQQQVGA.

They are located at the bottom of the images, and the numbers are different for each resolution. (4 for QQQVGA and 7~8 for QQQQVGA)

This can be clearly seen with GRAYSCALE instead of RGB565.

Currently, I'm working with OpenMV M7 and I've upgraded the firmware with the latest version.

Can anybody help me with this?
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kwagyeman
Posts: 2796
Joined: Sun May 24, 2015 2:10 pm

Re: Strange noisy lines on QQQVGA images

Postby kwagyeman » Thu Dec 27, 2018 1:20 am

That's due to an issue with the JPEG compression algorithm, this is a bug in the firmware I've been ignoring. It's due to use padding the JPEG image with zeros versus extending the pixels indefinitely from the edge when the image is not a multiple of 8. Um, yeah, let's get this fixed now. Make the image a multiple of 8 pixels in the mean time to fix.
Nyamekye,
want2bfree
Posts: 2
Joined: Wed Dec 26, 2018 8:42 pm

Re: Strange noisy lines on QQQVGA images

Postby want2bfree » Thu Dec 27, 2018 2:31 am

Thanks a lot for your quick and kind reply. :-)
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kwagyeman
Posts: 2796
Joined: Sun May 24, 2015 2:10 pm

Re: Strange noisy lines on QQQVGA images

Postby kwagyeman » Thu Dec 27, 2018 2:32 am

Make a bug on github for this.
Nyamekye,

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