Using invisible inks with IR sensitive camera to read instructions from QR Codes, April codes or Glyph for Indoor Navigation
Here I could have used a extra pair of hands , but it was just a quick test before bed after filling cartridges. I overplayed the IR ink onto the UV and the contrast really pops! Much better that IR on white paper by itself, when UV light is off you can see the camera picks up the IR ink on white paper as dark gray. Remember the longer term is invisible tags which in most cases means clear or Matt clear adhesive labels on printable sheets.
The pictures loaded in weird places on my phone so I will fix that tommorow on a pc.
IR only with the IR camera-
I filled cartridges will all the inks I have. I am likely to use noodlers and the UV absorbing ink , but I will start testing different labels soon. I picked up a Epson Workforce printer that uses these cartridges for 89 dollars from Office Depot. I believe I will dedicate the printer to making these invisible tags as to not mix inks.
Noodlers White versus UV yellow, very close , but the yellow is 5 times the cost!
ok so the UV inks I ordered made for a inner cartridge came in. I am slightly disappointed because the red is practically non existent. Anywho I compared them to noodlers ghost bullet proof inks and the white and green inkjet inks were much brighter. As I mentioned before I am considering using both IR and UV for maximum contrast in any lighting conditions or lack there of.
All are normally invisible without special lighting , filters or camera.
Top - not visible is magenta
2nd- white UV
3rd- blue UV
4th -green UV
5th- Noodlers Ghost UV
Tests against white paper is neeto,but the goal is to make invisible markers so I will print onto Matt or clear plastic. I put some on my finger of the green as well as the noodlers ghost white, the green is a tiny bit brighter. It is so close!!
Next is to start filling ink cartridges
This is UV ink on normal white paper, with a drawn white, of course the marker pen is 2mm tip . You can use your phone with a QR code to read by looking at this picture. It is my email address as a sample. The edges are not sharp, but my cell phone still reads after a couple seconds. I think this is good enough to proceed to the next step which is printing UV ink through an inkjet printer so the code is sharp and readable from afar.
Here is a UV reactive ink from Noodlers, a UV ink manufacturer for pens. One thing I noticed it is very thin , so it wets the paper more, I think I need a substance that has more UV pigments inside. This is the first UV tests. I want to have at least two inks in QR codes. The reason has to do with a variety of lighting conditions, different inks work better. Low light for example UV is king, but daytime IR absorbing looks grey even in daylight. QR codes can be any color, they operate on principles of contrast. As long as one is brighter than the other is should work.
So the video was uploaded sideways because that's apparently what my phone wanted. Good news is I'm switching to a galaxy Note 3 in a day or two. Looks like this will work fine and now I can get back to building beer bot. The next step is figuring out how many codes I want to use. I will need to buy a compass I believe next.
it's a very short video just showing that the code cam be moving some as long as it's slow enough to grab a frame. I also tried reading the code without the IR light and it would not read at all without direct illumination at 7 ft away using a 400 x 400 line Qr code.
Here is the setup I threw together with 850nm leds I already had and how it works.
Here you see the IR first test on a ceiling QR code at 7ft 4 inches away and the code way crooked , wrinkled and my dog tore a edge off and it consistently read it. The IR light us invisible to the naked eye and mostly invisible to modern cameras due to IR filters. After popping my EZ cam filter out the QR code is now read even better than when I illuminated it with a 1 watt led. It was even able to read the smaller Qr code at that distance so I see that IR illumination is much more effective than white light. I was pretty "geeked out" when I saw it literally worked better that using visible lighting. The camera also did not need to constantly adjust to the white balance like when I was using the super bright white led. Now I just need to figure out how to read the orientation of the QR code when read and that will always tell the robot which direction it is facing.
This last pic shows the inside of the lens where I popped the filter out. Honestly the camera is much more sensitive in low light without the filter and doesn't significantly effect the picture quality as far as color. But clarity in low light , wow! I popped it out with the tip of a xacto knife and if you kept it could easily be popped back in at any time.