JPEG camera video pixelated

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plurapal
 
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JPEG camera video pixelated

Post by plurapal »

We notice variable video quality when displaying video generated by Adafruit serial TTL JPEG camera units on a TV. At the low end the range, the video is pixelated more than the high quality video coming from other camera units. The pixelation interferes with focusing we want to perform. What causes the pixelated video and how to prevent it?

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adafruit_support_mike
 
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Re: JPEG camera video pixelated

Post by adafruit_support_mike »

That's just how the camera module works. There are no settings to control it.

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plurapal
 
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Re: JPEG camera video pixelated

Post by plurapal »

Thanks Mike. Why do we see varying video quality across nominally identical camera units?

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adafruit_support_mike
 
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Re: JPEG camera video pixelated

Post by adafruit_support_mike »

Are you testing multiple cameras at the same time/same conditions?

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plurapal
 
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Re: JPEG camera video pixelated

Post by plurapal »

Essentially yes. We use a focusing fixture with a target image that does not change. We focus camera units sequentially, one camera unit after the other. For some camera units large pixels appear on a video monitor, obstructing quality focus. For other camera units, the monitor displays tiny pixels that allow quality focus.

What causes the varying pixel size across camera units?

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adafruit_support_mike
 
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Re: JPEG camera video pixelated

Post by adafruit_support_mike »

It's probably a result of the JPEG encoding acting on differences in the sensor data. JPEG is an inherently lossy compression method, and it's hard to predict what will be lost.

You can check through the options in the CommTool to see if any of those improve your results:
https://learn.adafruit.com/ttl-serial-c ... -comm-tool

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plurapal
 
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Re: JPEG camera video pixelated

Post by plurapal »

Please realize that we focus cameras by video then gather still images with the focused cameras. Only the video shows large pixels (for some camera units). Still images gathered by a camera displaying large pixel video during the focus step do not have large pixels.

How could JPEG compression (a digital image compression) affect composite video, which I understand to be analog protocol?

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adafruit_support_mike
 
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Re: JPEG camera video pixelated

Post by adafruit_support_mike »

Post some of the images you're getting please.

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tommi20
 
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Re: JPEG camera video pixelated

Post by tommi20 »

while we focus cameras then gather the still images with the focused cameras, i think its pretty much easy, but needs a good eye dont you think ? keep it sharp guys, needs more suggestion here about the pixelated jpeg

_____________

Es Krim

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plurapal
 
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Re: JPEG camera video pixelated

Post by plurapal »

At your request, I tried to to attach a photo of video produced by an Adafruit camera unit on a Samsung TV. The pixelation of the image interferes with lens focusing.

I get the following error message: "Oops! There was a problem submitting your post. Please try again."

What to do? Is there a size limit on submitted files?

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adafruit_support_mike
 
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Re: JPEG camera video pixelated

Post by adafruit_support_mike »

Yes. The forum limits file sizes to 1MB maximum.

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plurapal
 
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Re: JPEG camera video pixelated

Post by plurapal »

Thanks. I post a photo of pixelated display produced by one Adafruit camera unit.
Attachments
Adafruit-X (pixelated).jpg
Adafruit-X (pixelated).jpg (857.69 KiB) Viewed 1034 times

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plurapal
 
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Re: JPEG camera video pixelated

Post by plurapal »

Now I post a good, non-pixelated image produced by another Adafruit camera unit.
Attachments
Adafruit-D (good).jpg
Adafruit-D (good).jpg (734.61 KiB) Viewed 1034 times

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adafruit_support_mike
 
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Re: JPEG camera video pixelated

Post by adafruit_support_mike »

Yeah, it looks like the compression ratio on unit X is higher than the compression ratio on unit D.

The image from unit D does have some pixellation, which you can see along the edges of the dark/light boundaries. It's most visible as a lighter halo along the light side of an edge. The block size is smaller though, which indicates a lower compression ratio.

Check the compression settings using CommTool and see how they compare.

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plurapal
 
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Re: JPEG camera video pixelated

Post by plurapal »

Thanks Mike, I determined that the resolution of pixelated camera unit X was less than camera unit D . After increasing camera X resolution to 640x480, image quality improved to that of camera D. Thanks for the help.

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