Color Detection - Electronic Circuits Projects Diagrams Free

demestav · 16th February 2005, 02:35 AM

Hello. I was wondering how a low budget color detection can be possible. I have seen in another threat that 3 LED (R,G,B) can be used and measure the intensity of light. But i have seen the LEGO MINDSTORM sensor that has only on LED (i think). I there such a component?

Thank you

zachtheterrible · 16th February 2005, 05:50 AM

There are single LEDs that has RGB in it, so that it is a multicolor LED.

demestav · 16th February 2005, 07:10 PM

Thank you zachtheterrible for your reply. So i guess mesasuring the reflection is the only solution? :?:

Thank you

Dean Huster · 16th February 2005, 08:25 PM

One solution I saw blasted a white LED at the sample and three filtered receivers measured the intensity. You had to put the standard sample under the detector and store the resulting readings as a "color". The simple system I saw was a demonstration for sorting m&ms into their various colors.

Dean

zachtheterrible · 16th February 2005, 08:45 PM

If three LEDs could do it, a single multicolor LED i would imagine could do it. It has four leads, one for red, one for green, and one for blue, and one for ground.

demestav · 17th February 2005, 10:36 PM

Thank you for your replies. I will try it out.

demestav · 6th July 2005, 11:08 AM

Hello. I back on this project and now i really need to find something simple and quick. The RGB LED would be well outside my budget. I think it should work with only one trans-receive IR module. However it would be great if someone could suggest a IR component to buy.

Thank you.

audioguru · 6th July 2005, 11:21 AM

A trans-receive IR module works with IR, which is infrared that has a frequency lower than visible light. It might pickup a small reflection from a red object, because the frequency of red is near the frequency of IR, but it wouldn't pickup an IR reflection from another colour.

**mechie** · 6th July 2005, 11:36 AM

Quote:

Originally Posted by demestav

I really need to find something simple and quick.

What kind of resolution are you after?
Are you trying to resolve shades of the same colour or just differentiate between, say, red, green and yellow?
What ambient lighting is there or is this a sensor that gets very close to (touches?) the object?

Would a simple torch bulb be OK for illumination and three LDRs, each with a colour filter (primaries or secondaries or "Quality Street" sweet wrappers) work as detectors?

demestav · 6th July 2005, 11:55 AM

Quote:

What kind of resolution are you after?
Are you trying to resolve shades of the same colour or just differentiate between, say, red, green and yellow?

Well I want the most basic color resolution possible!!!! Let's just say to seperate black from white.

Lego mindstorms have a IR module which can distinguish varius color (i tried it) and has only one receiver and one transmitter.

Thank you for your quick replies...

audioguru · 6th July 2005, 12:48 PM

Quote:

Originally Posted by demestav

I want the most basic color resolution possible!!!! Let's just say to seperate black from white.

Do you want colors or do you want black and white? Pure white is easy to detect since it contains all colors including IR. A trans-receive IR module would be able to give high resolution to the amount of IR that is reflected by different white samples. A redish grey might give the same output as a greenish white.

Quote:

Lego mindstorms have a IR module which can distinguish varius color (i tried it) and has only one receiver and one transmitter.

I couldn't fing a link to your LEGO color test, but found one where the LEGO IR was reflected off two LEGO bricks and the test was repeated using bricks of different colors. All colors including black (it was probably shiny) reflected some IR, red and yellow reflected the same amount and other colors a lesser amount. It could probably determine the LEGO bricks that reflected IR at different amounts from each other. http://www.io.com/~woodward/lego/
It is not the same as color resolution.

demestav · 6th July 2005, 01:16 PM

Quote:

Do you want colors or do you want black and white?

I just want to able to understand two different colors, what ever those colors are.

So what you are saying is that i will use a IR transmitter and the IR receiver indication will vary (enough to be detected) according to the color (black or white) of the object. I there any particular IR transceiver that you suggest me to use???

Thank you.

audioguru · 6th July 2005, 01:56 PM

Black and white are not colors. They are the absence of reflected light and the presence of reflected light. Since you are using only IR, your indication will have a few unknown color variables. A bright green or blue reflected color would give the same indication as a dim red reflected color, and many other color combinations would be the same.

I wouldn't use IR to detect colors, I would use an RGB LED or 3 separate ones, and 3 light detectors with color filters. With the correct choice of LED and filter colors I would have very good resolution of any color.

lord loh. · 6th July 2005, 02:45 PM

A few friends of mine use a light detecting resistor and an OP-AMP to detect colours.

According to them, the resistance of the LDR was dependent on the colour of light incident on it. They first cliberated the opamps for a few colours.

I do not believe that this shall be very accurate but defnitely low cost.

demestav · 7th July 2005, 07:53 PM

Thank you for your answers.

Since i have already oredered a IR tranceiver for distance measuring purposes, I will test it next week and i will let you know for the result.

Thanks again.

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16th February 2005, 02:35 AM	(permalink)
demestav	Color Detection Hello. I was wondering how a low budget color detection can be possible. I have seen in another threat that 3 LED (R,G,B) can be used and measure the intensity of light. But i have seen the LEGO MINDSTORM sensor that has only on LED (i think). I there such a component? Thank you

16th February 2005, 05:50 AM	(permalink)
zachtheterrible	There are single LEDs that has RGB in it, so that it is a multicolor LED. __________________ I'm no electronics god, i just talk too much.

16th February 2005, 07:10 PM	(permalink)
demestav	Thank you zachtheterrible for your reply. So i guess mesasuring the reflection is the only solution? :?: Thank you

16th February 2005, 08:25 PM	(permalink)
Dean Huster	One solution I saw blasted a white LED at the sample and three filtered receivers measured the intensity. You had to put the standard sample under the detector and store the resulting readings as a "color". The simple system I saw was a demonstration for sorting m&ms into their various colors. Dean __________________ Dean Huster, Electronics Curmudgeon Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines). R.I.P.

16th February 2005, 08:45 PM	(permalink)
zachtheterrible	If three LEDs could do it, a single multicolor LED i would imagine could do it. It has four leads, one for red, one for green, and one for blue, and one for ground. __________________ I'm no electronics god, i just talk too much.

17th February 2005, 10:36 PM	(permalink)
demestav	Thank you for your replies. I will try it out.

6th July 2005, 11:08 AM	(permalink)
demestav	Hello. I back on this project and now i really need to find something simple and quick. The RGB LED would be well outside my budget. I think it should work with only one trans-receive IR module. However it would be great if someone could suggest a IR component to buy. Thank you.

6th July 2005, 11:21 AM	(permalink)
audioguru	A trans-receive IR module works with IR, which is infrared that has a frequency lower than visible light. It might pickup a small reflection from a red object, because the frequency of red is near the frequency of IR, but it wouldn't pickup an IR reflection from another colour. __________________ Uncle $crooge

6th July 2005, 01:56 PM	(permalink)
audioguru	Black and white are not colors. They are the absence of reflected light and the presence of reflected light. Since you are using only IR, your indication will have a few unknown color variables. A bright green or blue reflected color would give the same indication as a dim red reflected color, and many other color combinations would be the same. I wouldn't use IR to detect colors, I would use an RGB LED or 3 separate ones, and 3 light detectors with color filters. With the correct choice of LED and filter colors I would have very good resolution of any color. __________________ Uncle $crooge

6th July 2005, 02:45 PM	(permalink)
lord loh.	A few friends of mine use a light detecting resistor and an OP-AMP to detect colours. According to them, the resistance of the LDR was dependent on the colour of light incident on it. They first cliberated the opamps for a few colours. I do not believe that this shall be very accurate but defnitely low cost. __________________ Bharath Bhushan Lohray. M.Sc. Electronics.

7th July 2005, 07:53 PM	(permalink)
demestav	Thank you for your answers. Since i have already oredered a IR tranceiver for distance measuring purposes, I will test it next week and i will let you know for the result. Thanks again.