# Infragram Sandbox infragram-sandbox

The [Infragram Sandbox](http://infragram.org/sandbox) is a browser based tool for experimenting with image compositing, intended for use with Public Lab [Infragram cameras](/wiki/infragram). Read [this research note](/notes/warren/08-17-2013/infragrammar-compositing-infrared-images-with-simple-mathematic-expressions#c6664) and watch this short video to get a quick idea of how to use it: ##Infragrammar Infragram Sandbox uses simple math expressions, which are actually written in JavaScript. Here are some examples: * [NDVI](/wiki/ndvi) = (R-B)/(R+B) for -1..1, or for 0..1 (((R-B)/(R+B))+1)/2 in the Monochrome input * ENDVI = ((R+G)-(2*B))/((R+G)+(2*B)) which MaxMax uses for its vegetation stress cameras, in the Monochrome input * A colormapped NDVI, scaled to emphasize differentiation: ((R-B)/(R+B)-0.2)*-720, in the Hue input, and tweaking the 0.2 value to between 0.1 and 0.9 ([read more here](/notes/warren/08-24-2013/infragrammar-with-hsv-color-model)) * (add yours here) ###Math Infragrammar can use [JavaScript math functions](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math). These include: * Math.log() - logarithms * Math.abs() - absolute value * Math.sin() - sine ###Sliders You can also link an equation to a slider; for now we are using the letter "X" to represent this value, but in the future, any string represented as {mystring} will generate a slider called "mystring". Move the slider to try different values in real time. [![infragrammar](http://publiclab.org/system/images/photos/000/001/174/medium/Screen_Shot_2013-08-17_at_11.52.00_AM.png)](http://publiclab.org/system/images/photos/000/001/174/original/Screen_Shot_2013-08-17_at_11.52.00_AM.png)...

Author Comment Last activity Moderation
mathew "this is really cool. I made mine out of paper and tape " | Read more » about 9 years ago
mathew "I'm surprised at the IR passing of the Powershot. nice research. really should buy some of those NIR LEDs myself. " | Read more » about 9 years ago
cfastie "Is the levels stretching you are referring to the same thing as histogram stretching? If so, it should be high priority. If the look up table feat..." | Read more » about 9 years ago
warren "As i pointed out in the comments here yesterday, this HSV approach is pretty interesting and conceptually fun, but not ideal for real work with LUT..." | Read more » about 9 years ago
warren "Corrections made re: order of operations, thank you Chris for a sharp eye and a clearer memory of how to do basic arithmetic! And you said you coul..." | Read more » about 9 years ago
warren "Mathew only sent me one raw image: " | Read more » about 9 years ago
cfastie "It looks like you've done a good job matching the NDVI index from the two cameras. It's hard to evaluate the meaningfulness of the NDVI images beca..." | Read more » about 9 years ago
nedhorning "I think it might be possible to work on a simple calibration process that could be used to get decent NDVI values. I don't think there is much a us..." | Read more » about 9 years ago
mathew "This isn't working for me either. I get a red or blue image, but not a NDVI-style color map. " | Read more » about 9 years ago
warren "...the plant pixels will have the biggest values for both R and B and the difference between them is therefore likely to be bigger. Yeah, the idea..." | Read more » about 9 years ago
PeeBee "Thanks cfasie. I understand now the exposure issue you raise. But you seem to assume the different exposures are an unknown, which it strikes me ..." | Read more » about 9 years ago
cfastie "To compute NDVI, you have to know the relative amount of light in a visible and an NIR band being reflected from plant leaves. The difference betwe..." | Read more » about 9 years ago
air_maiden "I too am interested to see whether a non-modified camera and a camera with the IR filter removed can be used to calculate NDVI. Could you please cl..." | Read more » about 9 years ago
cfastie "That's a really clever idea, and I think it might work. However, it assumes that: The photos must be simultaneous if anything in the scene is cha..." | Read more » about 9 years ago
PeeBee "Thanks cfastie. I don't think I understand the need for the Wratten filter. My understanding is: A camera with just the IR filter removed (i.e. n..." | Read more » about 9 years ago
zorn "Ah, thanks for the answers! Makes it much clearer now.... As i told before, i want to have the possibility to tae normal Pics and pure NIR.... I ..." | Read more » about 9 years ago
cfastie "I see what you mean when you say that the difference between the blue and red channels is correlated with the presence of plants. Your monochrome i..." | Read more » about 9 years ago
cfastie "Zorn, If you remove the IR block filter, the camera will take very strange photos because all three color channels (RGB) will have lots of NIR ligh..." | Read more » about 9 years ago
warren "In short, while you've clearly shown there is IR in all 3 channels, there is still a reasonably good signal/noise ratio difference between 2 channe..." | Read more » about 9 years ago
warren "Thanks Chris, but I'm not sure I agree that we're just seeing brightness due to infrared. I'm not saying this is NDVI -- it seems to work in the re..." | Read more » about 9 years ago
cfastie "If you have two cameras, and your goal is NDVI or false color infrared, the best way to get what you need is one unmodified camera and one with the..." | Read more » about 9 years ago
PeeBee "I am new to this field, and am busy trying to mod a Mobius by removing the IR filter and adding a blue (red remove) filter. I have made a side by ..." | Read more » about 9 years ago
cfastie "More tests are definitely merited. First, I was assuming that Carl was using a Rosco blue filter, and my original conclusions were based on that. ..." | Read more » about 9 years ago
warren "With the new Infragram.org, Mathew Lippincott and I did a new attempt at using these images and exploring the Mobius as a potential Infragram-modda..." | Read more » about 9 years ago