Any chance of getting color information for each pixel?

[davaughn]

Hi,

This work is absolutely amazing and precisely what I’m looking for to move my image processing off my laptop and onto an Arduino board. I’m doing some color calculations on each pixel in a frame, make a mod to each pixel, and then I want to export the new frame, in real-time, out. It seems like the Video Experimentor Shield is exactly that, but monochromatic- any chance of getting (any bit-size) color information in the future? Or is that a hardware impossibility?

best,
Don

[Michael]

It’s not possible to interpret or generate color with the very limited hardware in an Arduino. The TVout library uses 1-bit depth low res video, and it generates a composite signal by bit-banging it out digital pin 7. Primitive but effective. My enhancements that allow capture of information use the primitive method of measuring the voltage on the incoming signal relative to a threshold. If the voltage is higher than the threshold, then the pixel is “on”, otherwise off. This is the job of the ATmega328 analog comparator. All very primitive because of the hardware.

[Anonymous]

OK, I fully appreciate that Arduino can’t do color image processing. But I’m thinking of a different application and wonder if it’s possible to get any color info at all from composite video using your hardware. I’d like to build an “ambient light” system that lights the space behind the TV with RGB LEDs, such as this example:
http://www.instructables.com/id/Java-Microcontroller-LED-TV-Ambient-Light/

The above example uses a PC to process the video stream, which is then fed to the TV monitor. Instead, I’d like to monitor the composite (or component) output of a TV and drive RBG LEDs based on the “average color” of the image. Since you have a big head start in video processing, I thought I’d ask if you have any ideas how to accomplish that. Probably not with an Arduino, but maybe an ARM Cortex or some such thing.

Note that this idea does not involve any TV Out or generation of overlays. I just want to access the color info from a composite/component output to drive one or more RBG channels. Does that sound reasonable?

Thanks!

[Michael]

I understand what you are trying to accomplish. I don’t think the ATmega328 is fast enough to sample an analog waveform fast enough to figure out its frequency (color). The color of each pixel is defined by the voltage waveform at that moment. The ADC in the Arduino takes several clock cycles to perform an analog conversion, so you’d never be able to sample fast enough to learn about the waveform in the timespan of a pixel. If the color of the whole screen is similar, perhaps there’s a way to sample it quickly and deduce the frequency. This would involve writing assembly I think.
I’m not sure what other hardware would accomplish this, but probably a chip that is designed to process a composite signal. Certainly not the $3 ATmega328 and $1.50 LM1881 chips.

[lucy56@er]

It is a hard work to do this,but if you use the 10.1 inch Laptop to handle it,will be more high effeicient.

[mikky7]

TV and drive RBG LEDs based on the “average color” of the image. Since you have a big head start in video processing, I thought I’d ask if you have any ideas how to accomplish that.
Probably not with an Arduino, but maybe an ARM Cortex or some such thing.

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[Michael]

TV and drive RBG LEDs based on the “average color” of the image.

Is that a question? You need a tuner if you want to do this with a TV signal, then you need a computer to process the video stream somehow.

[Hansaplastique]

I’m thinking of a similar project like Jeff and was wondering if VE could capture the video in very low resolution in color.
Not sure if this is possible, but capture video in for example 4 x 3 pixels (total for the entire screen) in color.
This would keep the amount of data very limited and might be sufficient to use for driving LED colors?

[Michael]

You cannot capture color information with the Video Experimenter. The chip doesn’t do it.

[Hansaplastique]

Bummer … thanks Michael for the reply … 🙂

[zohaa]

yup ,thanks

[Author]

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