Digital Filter Construction Project

[AstroGuy]

Originally Posted by bojan

Hmm..
To my understanding, LCD screen consist of small segments (pixels), which are activated/deactivated and scaled/dimmed to achieve the desired colour saturation and luminance on the area much larger than one segment (pixel).
Also, the filtering characteristics of the LCD pixels are not according to standard, used in stellar colorimetry.
Compared to combination of b/w CCD camera and individual RGB filters (on the rotating wheel) the LCD in the light path (with it's low transmission and pixelisation that will affect the resolution of the image) must be inferior.
Personally, I can't see how this idea could be useful.
Could you give us some more detailed theoretical background? For example, how do you intend to calibrate your measurements?

If you need calibration, there are RGB sensors with supporting circuit board on eBay that have extremely accurate colour detection capabilities. They are also not too expensive. You will however need some basic electronic knowledge to incorporate and use them. The sensor itself has on board calibration for itself in hardware and software. If I remember correctly they are about $39 and have a 12mm lens port so a standard webcam to 1.25"/t thread adapter can be used to interface with a scope's 1.25" visual/T2 interface. Hopefully they will come down in price eventually soon.

My advice is, if you are going to get one of those webcam adapters. Don't get the one's made from Delrin, they can ruin your CCD, and because they can easily be static charged, minute delrin particles tend to contaminate the CCD with a vengeance. Good quality aluminum ones are more reliable, stronger and in most cases, more cost-effective.

At this point in time the main objective is just colour filtering for simple enhancement of moon and planetary views. Later I will experiment more with spectroscopic functions and the like.


Regards...

[bojan]

Well, my impression about this article is quite the opposite: it is describing the 1-pixel technology, not discrediting it.
The reason I posted this link was to show that this is not a new concept.

Originally Posted by AstroGuy

This image of the single pixel camera in my opinion is a fake.

If you bring it into photoshop you can see that the colour channels are not even RGB, instead they are indexed. Complete fake used to discredit the single pixel camera technology in my opinion. Quite dubious And to top it off it shows a current Hi-resolution image (probably taken with modern DSLR) against an image that was taken with the single pixel camera technology from 1996.

Even if this example was accurate, don't forget that in 1996 we still used DSTN (256 colour) LCD not TFT LCD (close to true colour).

That's like comparing the original ford car of the 1900's with a porsche of 2010. Complete fake and bias example of this technology. I think the author of that article had a grievance with the current developers of this technology.



Regards...

[AstroGuy]

Originally Posted by bojan

Well, my impression about this article is quite the opposite: it is describing the 1-pixel technology, not discrediting it.
The reason I posted this link was to show that this not a new concept.

I don't know Bojan, I got the impression from the author's writings that, this technology was being represented in a negative light. Especially by showing examples that are much older and inferior than currently developed images.

It would not surprise me in the least if the author may be on the payroll of some well known manufacturer of a competing technology. It's not the first time a similar scenario has developed. I know this concept is not new, I myself experimented with this technology/concept over 20 years ago.

[bojan]

Here you have more about this.
http://dsp.rice.edu/cscamera

[AstroGuy]

Originally Posted by bojan

You are mixing here two totally separate concepts.

350nm is the bandwidth of visible, white light, yes... but all the LCD filter does is, it is subtracting certain amount of band from while light to create for us the PERCEPTION of specific colour.
Number of available colours (or colour resolution) is NOT the same thing as wavelength resolution.


If you want to isolate various single lines from spectrum, you have to have a tuneable, narrow band filter. Period. No LCD filter can do this.
The single spectral lines can't be "synthesised" or made from primers.. their approximate colour maybe (if their colours are inside the colour space, determined by standard primers).. but I can tell you right away that for H-alpha this is not the case - the colour of this light is well outside any standard colour space and it cant be reproduced accurately).
And, once again, this is about colour (perception) we are talking about.
The wavelength of light (spectral line) is totally different thing.

More information on the subject is available here:
http://en.wikipedia.org/wiki/Colorimetry

Bojan,

The way RGB LCD panels filter lightwaves is by creating a variable width/tuned polarized micro gate. This is what tunes in, or tunes out different visible spectral wavelengths. There is NO perception of colour! it's real.

[bojan]

Originally Posted by AstroGuy

Bojan,

The way RGB LCD panels filter lightwaves is by creating a variable width/tuned polarized micro gate. This is what tunes in, or tunes out different visible spectral wavelengths. There is NO perception of colour! it's real.

Eugeino,
I must disagree with this... this is not how LCD display work (at least this not what I know about LCD's).
http://en.wikipedia.org/wiki/Liquid_crystal_display


Please provide me with relevant link with more information.

[AstroGuy]

Originally Posted by bojan

Here you have more about this.
http://dsp.rice.edu/cscamera

Bojan,

I don't see how that relates to this thread on the LCD Digital Filter Project? It seems like a totally different technology altogether. Most likely suited for a totally different application. Sorry, I don't see the relevance.

I pointed out the single pixel camera technology because it uses an LCD colour mask similar in principle to what we are trying to accomplish here, and to show that LCD colour filtering works period. Nothing more.

I respect your thoughts and ideas on this and have established that you don't think it will work. Well, I've shown you in principle that LCD colour filtering does work. You still have not provided any evidence or links that it does not work. Don't get me wrong, I don't want to debate the issue, I just don't want to keep going around in circles on this one. That's not to say other members are not welcome to respond to your claims.

In regards to providing links to how a LCD panel filters light:

I don't have any links at the moment, this is information I researched many years ago from books and articles on the manufacturing processes and technical functionality of the LCD matrix technology. I'm sure if you GOOGLE the subject it will explain it to you in more detail than I can provide at the moment. If I do come across any links in my travels I will post them here for you and others to review.

Bojan you are a very persistent fellow I get the impression that you are trying to discourage me and others from going ahead with this project because you are trying to save me/us the heartache, don't worry, please save the "I told you so" for later if it's applicable, after I've concluded the tests I'll have some additional reporting on this. You can then make up your mind(s) if it's worth pursuing. After all this is also an exercise in FUN!


Regards...

[bojan]

Originally Posted by AstroGuy

Bojan,

I don't see how that relates to this thread on the LCD Digital Filter Project? It seems like a totally different technology altogether. Most likely suited for a totally different application. Sorry, I don't see the relevance.

It doesn't, of course.. it is just some more info for you in relation to one pixel camera.


As far as LCD panel works, well, you were the first one who said the narrow band filtering will work using LCD filter
So, it is up to you to show us how this would be possible..

Based on what I know about LCD's, I simply can't see how..
I do accept my understanding about those things may be insufficient- this is definitely a possibility. I googled a lot on the subject but I am not much more knowledgeable after this exercise... I certainly want to learn about new things, so any new information on the subject would be highly appreciated

[CraigS]

I've got an answer …

Right technology … different application … I've been looking for a way to thwart those pesky radar cameras.
All I need is an LCD panel to cover my number plate, and whenever I go through the camera zone, I press the button on my dashboard and it turns the number plate black.

Bingo !! .. No more speeding (or red light camera) fines !

Phase #2 is to automate it so I don't have to push the button !!

Disclaimer … I did not write this !!



Cheers
PS: But all royalities can be sent thru my PM box.

[AstroGuy]

Originally Posted by CraigS

I've got an answer …

Right technology … different application … I've been looking for a way to thwart those pesky radar cameras.
All I need is an LCD panel to cover my number plate, and whenever I go through the camera zone, I press the button on my dashboard and it turns the number plate black.

Bingo !! .. No more speeding (or red light camera) fines !

Phase #2 is to automate it so I don't have to push the button !!

Disclaimer … I did not write this !!



Cheers
PS: But all royalities can be sent thru my PM box.

hmmmmm........not quite what this project was intended for I'm afraid