Digital Cameras as Scientific Instruments Mort Sternheim Rob Snyder NSTA April 12, 2013 DRL

STEM DIGITAL Summer Institute STEM DIGITAL Images in Geochemical Investigations: Teaching Analysis with Light June , 2013 at UMass Amherst Waiting list Online course in Fall, 2013 Middle & High School Science, Math, and Technology Teachers Teams of science and computer teachers encouraged Participants MUST bring a digital camera, and are encouraged to bring a laptop computer $75/day stipends ($375 total), materials, parking, lunches Housing for those outside the commuting radius 3 to 6 graduate credits available at reduced cost; free PDP's (Professional Development Points)

The Big Idea Digital cameras and computers are widely available for students and teachers. However, they are mainly used for documentation: creating PPT presentations, handouts, posters, etc. You can measure Spatial information: distances, areas, angles Changes over time – plants, moving objects Intensities (albedo) Color (spectral) information Applications to studies of air quality, water quality, arsenic contamination, diffusion, climate change …

Analyzing Digital Images Software Software package developed by John Pickle, Concord Academy (formerly Museum of Science, Boston) Free, student friendly, for Windows and Mac Spatial, spectral, intensity, temporal analysis tools You do not have to master all of ADI to do simple tasks You do not have to have a computer lab New beta-test Java version is faster, fixes large RAM problems ADI, color basics, digital image basics, MovieTracker programs Downloads:

Today What the software can do Color basics Demonstrations (if time)

Color Basics Program Adding lights Adding pigments

Image Basics Program 512 x 512 pixels15 x 16 pixels

Measuring albedo with ADI Melting Arctic ice or snow exposes water or tundra, decreasing the reflection of sunlight or the albedo This is one reason climate change is greatest in Polar Regions Graph colors along a line Snow Muddy turf Snow reflected intensity ~ 85 units Muddy turf ~15 units

Measuring lengths

Measuring areas with the polygon tool

Water quality: dissolved organic matter - study effects of various treatments B : Oak/Maple Aged 7 mo I : Goldenrod Fresh Blank : Tap water No leaves

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Line Tool: Color along line xcz BI Blank

Aiptasia pallida as a Model Organism for Effect of Environmental Stressors on Coral Bleaching Amherst Regional Middle School NSF STEMRAYS after- school club student authentic research project

Aiptasia pallida is a sea anemone which houses symbiotic dinoflagellates that are responsible for the brown color of the tentacles. They are easy to culture and can test the effects of stressors (changes in light, temperature, pH) on the release of the symbiotic organisms. Coral also contain symbiotic organisms. Coral bleaching occurs when the coral is stressed and releases these organisms. Coral are difficult to culture in a lab..

Using ADI, a line is drawn on one individual. Aiptasia are fixed in place, so same line can be drawn later for comparison after it is subjected to a stress.

The Diffusion of CO 2 Through Gelatin as a Model for Diffusion of CO 2 Through a Cell Over Time Diffusion is one way materials move into and out of cells. Gelatin has a consistency similar to a cellular matrix and can be used to show the movement of materials. A disk of gelatin is prepared with bromothymol blue, an acid- base indicator, and placed in a Petri dish. Carbonated water is added. A time series of photographs and their corresponding ADI graphs reveals the diffusion of CO 2 through the gelatin.

Control Gelatin Disk (water)

Gelatin disk exposed to carbonated water after 3 hours.

Teacher application: eye color I was sort of surprised at how quickly they learned to use it… Once I showed them the size of the rectangles I wanted for sampling colors, they just took off. The most interesting thing we discovered was that blue eyes are not blue! Sharon Cumiskey, 8 th grade, Plymouth, MA

More examples Used the ADI software to measure the grain size of known rock thin sections to identify the mineral composition. WOW it really worked and my five 8th grade accelerated Regents Earth Science classes had so much fun using it. Ray Szczerba, Clifton Park, NY Wind Turbine Lesson The Movie Tracker software, worked out well. Students were able to determine the revolutions per minute of their blades. I used this data as the determination for how well their turbine ‘functioned’. I will definitely continue with this analytical tool for the turbine project next year! John Nicholson, Freeport ME Middle School

Color Basics Inexpensive spotlights can be used to demonstrate: A set of primary colors of light. What happens if we mix pairs of primary colors. What happens if we mix three primary colors of light. Flashlights with color filters can also be used to experiment with colors of light.

Our Eyes Have Two Types of Photoreceptors Our eyes have two main types of photoreceptors called rods and cones. These cells are located in a layer at the back of the eye called the retina. Cones allow us to see colors. They are not as sensitive as the rods so they only work in bright light and are often described as red, green and blue cones. Rods are used to see in very dim light and only show the world to us in black and white. This is why you see only black and white when you are outside in the evening or in a dimly lit room.

Each type of cone detects a range of wavelengths. “Red” cones have a peak detection of greenish-yellow. “Green” cones have a peak detection of green. “Blue” cones detect principally blue and violet colors Which pair of cones might respond to yellow light?

Color processing begins in the eye’s cones. Signals are then transmitted through optic nerves to the brain where data processing continues. Our brain compares responses of cones to visible light and interprets a color. For example: “Red” and “green” cones both respond to yellow light.

Digital cameras have three different filters that cover an array of many sensors. Each sensor detects the intensities of light in a range of long wavelengths or medium wavelengths or short wavelengths that are transmitted through filters. Data is then transmitted to and stored in a memory card in the camera.

Our eyes and camera detect colors in somewhat similar ways. Our brain analyzes data it receives from the cones in our eyes. The ADI software program in a computer analyzes data it receives from the camera memory card.

The ADI “line tool” can analyze a photograph of yellow paint. The average intensities of colors detected along the line are: Red = 62.9%, Green = 45.61%. Blue = 0.33%

ADI can produce a graph that also illustrates that “red” and “green” sensors of a camera respond to light reflected from yellow paint This type of graph is produced with the line tool.

This is a photograph of a mix of red and green light. Average Intensities along the line are: R = 69%, G = 57%, B = 38% High quality lights in dark rooms result a much lower intensity of blue.

What does ADI reveal about differences between a mix of primary colors of paint and a mix of primary colors of light?

Here are two sets of primary paints that can be mixed. Cyan, Magenta, and Yellow pigments are often used to print many different colors. Elementary school students often learn that Blue, Red, and Yellow paints can be used to create many colors.

ADI also has a rectangle tool that can analyze a mix of primary paints or dyes. The relatively low RGB intensity levels in the rectangle are: Red = 11%, Green = 10%, Blue = 9%

A histogram reveals lower intensities of red, green and blue detected when blue, red and yellow paints were mixed together. Mixing primary paints produces a color that absorbs more colors of light so it is called a subtractive process.

Different colors of a paint, dye or ink absorb different colors of light. Blue paint absorbs principally red and green wavelengths of light. Red paint absorbs principally blue and green wavelengths of light. Yellow paint absorbs principally blue wavelengths of light. Mixing these 3 colors of paint absorbs a set of primary colors of light. The cones of our eyes are not stimulated very much and we perceive color as a black or muddy brown color.

The ADI rectangle tool can analyze the result of shining inexpensive Red, Green and Blue spotlights onto a screen. The relatively high intensities of RGB detected in the “white” light are: Red = 62.14%, Green = 59.94%, Blue = 60.36%

An ADI histogram also reveals fairly high intensities of red, green and blue light in the white light produced during the demonstration. Mixing primary colors of light produced a lighter color so mixing colors of light is called an additive process.

High quality spotlights could produce the complementary and white colors very well. Note: Any 3 colors from three different regions of the visible spectrum can be used as primary colors.

A Summary of Color Basics Eyes and digital cameras detect light in the red, green and blue ranges of the visible spectrum. Primary colors of light are different from primary colors of paints or pigments. Mixing three primary colors of light is additive, producing a lighter color increases the intensities of the primary colors detected by our eyes or a digital camera. Mixing three primary colors of paints is subtractive, producing a darker color and reduces the intensities of the primary colors detected by our eyes or a digital camera.

Contacts Mort Sternheim, Rob Snyder, Marie Silver, Project Manager, Web site: Materials, applications … Today’s materials: ADI software: