Ask MetaFilter questions tagged with transparent

Transparent Velveeta?

cleverevans — Wed, 21 Oct 2009 17:50:10 -0800

Is Velveeta cheese transparent before artificial coloring is added? Or is this just an Urban Legend?

Where do I find transparent coatings that show up in near-infrared photography?

kscottz — Thu, 16 Apr 2009 11:46:38 -0800

I need a non-toxic coating that is transparent under visible light but appears much darker/lighter in near-infrared photography. My dear chemist, physicists, and material scientists, I am working on a project where I want to coat uniform surfaces with a substance that appears transparent or semitransparent in normal human vision but shows up really well under near-infrared photography. My infrared camera is a USB web cam with the IR filter replaced with some flavor of IR-Pass filter. I should be able to make my own paint if you can point me in the direction of a pigment that will have the desired results. Bonus points for substances that are non-toxic.

I do computer vision work and I want to detect image features on substances that would otherwise look fairly featureless (like a wall, or a tabletop).

Those fancy markerboards on "ReGenesis"

gentle — Sun, 05 Oct 2008 10:40:19 -0800

On the TV show ReGenesis, the scientists constantly scribble with markers on big, transparent boards — here's a clip, and here's another. I am guessing that they are using fluorescent wet-erase markers, perhaps in combination with a black-light lamp to make the paint visible in such low light. Where can I buy a setup like this?

How do stickers that fade to transparency work?

Xoder — Wed, 24 Jan 2007 08:18:52 -0800

At my (security-sensitive) work we all get badges. Sometimes we leave them at home. Sometimes we need to bring a visitor in. Then we get temporary badges. These badges have an interesting fading sticker on them. How does it work? The sticker is actually in two parts, which I've seen assembled thusly: First, a red "EXPIRED" sticker with lots of bright red lines is placed on the plastic badge. Then a white sticker with the division name is affixed directly on top of that one.

As the day progresses the "EXPIRED" text becomes more and more visible. I've not yet had the gumption to take one home and see if the white sticker fades completely, but it appears that is what would happen. How does this work?

I asked one of the receptionists that passes them out, and he said that the red ink was bleeding into the white sticker. I find this implausible for two reasons: the sheets with the red stickers on them are stored folded and have no protective covering for any wet ink, and generally the backs of stickers are pretty impermeable to all but some nice solvents (at least in my experience) that would cause the adhesive to fail.

In addition, the red and white stickers become permanently bound together (I futzed with them at work a bit), but it's trivially easy to remove the red sticker from the card itself (good for the staff as they clearly have to do this every day).

Thanks in advance!

Browse html files inside a rar archive

Chuckles — Wed, 08 Mar 2006 17:12:42 -0800

I'm looking for a method to automatically open the index.html file within an archive and then allow browsing from there, without decompressing. Something like CDisplay, but for html files. Firefox plugin maybe? What matters is that it is supper easy.

I do not want to enable the XP built in zip support, I only want this to be 'visible' from within a specific application launched for the purpose.

Other tricks for treating archives transparently under tightly defined criteria will also be appreciated.

Is there php to create image overlays on the fly?

nomisxid — Thu, 02 Mar 2006 10:49:19 -0800

What technology could I use to create a transparent image overlay on the fly? I have an image on my website that gets used in a gazillion threads out on the internet. I have no issue with that, if I didn't want it showing up in GIS, I'd setup a robots.txt exclusion. I would like to say 'hi' to all these folks who, by direct linking to the image, ensure no one sees the original context. Something along the lines of pulling out the message board name from the referrer and displaying the original image request with a translucent/transparent overlay of some text along the lines of "welcome visitors from xyz, see the original article at http://my-lame-site.com/blahblah". Currently my website is built on php, and I know how to find the article I want linked from the image-name. I am wondering ...

1. is there a php module that will let me create transparent images from text strings?

2. how to redirect requests for the jpg to a php script

Chromakeyed transparent windows?

RustyBrooks — Tue, 24 Jan 2006 14:43:16 -0800

I have found programs that allow you to apply partial transparency to a window (in windows), but I'm looking for something a little different: chroma keyed transparency, like what is used in visual effects or on the weather report. I have two windows. I want one to sit on top of the other, and I want to choose a color on the top window, which will be totally transparent, so you can see the other window through it. I have programs that I use, like TweakWindow, which allow you to set partial transparency to the top window, and this is OK, but ideally I'd like to have parts of the top window be transparent, and parts not.

Does anyone know of a windows program that does something like this?

My most likely usage will be to have most of the top window be the transparent color, and the rest to have blocks of white with data in them.