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JPEG, GIF, PNG, TIFF…Huh?

Mar 21st, 2009 by

Using and archiving primary resources is a large part of many of the projects at our school.  Writing autobiographies or biographies and recording the stories of family members and veterans often include taking or scanning images of objects, letters, or photos. When scanning the question that is eventually asked is what format do I save in? to which I answer, save as a .jpg of course! right?

But a strange course of recent events made me question my answer. First, I lost over 1,500 digital images taken on vacation in London. Gone…not stored on my computer, not on my external drive, and the one disk labeled “London” won’t open. Second, I remember a video clip I saw over at Free Technology for Teachers on Data Rot. My ears pricked up when the acting Chief of Prints and Photographs at the Library of Congress commented that 16 million photos, prints and posters would be scanned and saved as TIFF files. TIFF files?

My sister and me, Canada 1964

Lastly, my mom gave me this image. On the back of the photo she wrote “the Pin up Girls”. (One of them is me and I’m not telling which one!) The photo is one a very few that I have of my vacation with my sister when I was five. I want to save a coy of it, so do I take the LOC’s advise and scan and save as a TIFF or go with the good, old JPG. What is the difference in file formats? I decided to investigate. Here is what I learned…

JPEG-Joint Photographic Experts Group.
If you’re working with a photograph or a highly detailed graphic with lots and lots of colors, and storage space is limited, JPEG may be your best choice. JPEG files make use of 16 million color providing the integrity of the color is preserved when the file is saved. Using lossy compression images saved in JPEG format are reduced in size by only removing color information that would not be normally detected by the human eye. However, each time a JPEG file is resaved in JPEG format more information is lost. Images composed primarily composed of lines or text may appear blurry when saved in a JPEG format.

GIF-Graphics Interchange Format
Pulling from 256 color GIF formats work well with images composed mostly of text in small font size, line drawing, black and white images, or blocks of a single color tone. If you save a highly detailed color image in a GIF format you may see major changes in color value, or tone. Individual GIF images can combined into an animated images with the use of an animation editor.

PNG-Portable Network Graphics
If you use a Mac and use the Grab utility or take screen snaps using Apple Shift 3, you’ve probably noticed that the snaps are saved as PNG files. PNG files have the best qualities of JPG files and GIF files. PNG files are compressed the same way JPG files, but result in files 5%-25% smaller then in a GIF format. Unfortunately some browsers do not displays the PNG format.

TIFF-Tagged Image File Format
If there was a Gold Standard for scanning formats, TIFF would be the awarded the title. The choice for most commercial and professional needs, TIFF files are not compressed; the result is no loss of data from original to digital format. The downside is file size; TIFF files can be much larger then a JPG file of the same image. If you are working with detailed and/or historic images, or you have a photo that you will be reprinting or re-saving multiple times, you may want to archive your images in a TIFF format.

In the end I followed the LOC’s advice. I saved as a TIFF file at 1.1mb compared to the 336kb of space needed for the JPG format.

Resources:
Image file format – TIF, JPG, PNG, GIF
Webopedia: Graphic File Formats
JPEG vs TIFF for Scanning Photos, Slides, and Negatives

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Posted in images, photography | No Comments »

Building Virtual Bridges

Mar 17th, 2009 by

Each spring our 5th graders complete a bridge building exercise. Working in teams, students take on the jobs of accountant, engineer, designer, and builder. Their task is to build a bridge out of toothpick, within a budget, and that can stand on its own. The bridge that can hold to most weight wins. The students love the unit, learning about  bridge designs, working cooperatively, and having lots of hands-on fun.

Today, over at the Official Google Blog, a different kind of bridge competition was announced, the SketchUp 2009 International Student Bridge Modeling Competition. Unfortunately for the 5th graders they are too young to enter this year, (you have to be 18 years or older) but why let a little detail like that get in the way of expanding their design talents by letting them loose in Sketchup.

Penobscot Narrows BridgeMaine has some incredible examples of bridge design from the historic Sewall’s Bridge in York, the carriage road bridges in Acadia National Park, to the very modern Penobscot Narrows Bridge. Playing and learning in a 3D environment which bridge would they be inspired to try to draw? Perhaps they might want to try designing Maine’s next great bridge or perhaps the world’s next great span. Where would it go? What design principals would they use to build their bridge? With their drawings complete, the teams can place the drawings into a GoogleEarth map to save and share. This is an opportunity to practice their lat/long skills, determine if their bridge matches the terrain of the area, and to show off their work.

Moving back to a hands-on challenge the student teams can now take their design from computer to toothpick? Does what looks good on paper work in the real world? The first time they try using Sketchup our fifth graders might make some mistakes, but so do grown-up engineers when moving from drawing board to model. But, what a great opportunity to ask: what did you learn, what did you try, and did you have fun.


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Posted in 21st century classroom, education, mashup | No Comments »

Happy Pi Day!

Mar 14th, 2009 by

March 2009 may well be remembered as one of mathematician’s all time-favorites. First we celebrated Square Root Day March 3rd, and today, March 14, take time we take time to celebrate perhaps one of the universe’s most famous numbers on National Pi Day

Defined as the ratio of circle’s circumference to its diameter, what I like about Pi is that it’s dependable; no matter the size of the circle, the value of Pi is constant, 3.1415926535 when rounded to 10 places.

But for mathematician’s Pi is also a very frustrating and obstinate number. Pi may be dependable when comparing circumferences and diameters, it can be irrational and transcendental. (Perhaps it was Pi’s transcendental nature that led to another age old truth, that you can’t fit a square peg into a round hole!)

Why does Pi deserve it’s own day each year? Because since the time of Archimedes, mathematicians have yet to find an end to Pi. It’s irrational nature stubbornly refuses to allow for the decimal value to repeat or come to an end. (Would you like to see what Pi looks like worked out to the first 10,000 digits? How about a million places?) But let’s not forget that it was Pi’s trillion digit length that allowed us to measure the size of the Earth to within a millimeter of accuracy and has kept programmers and their super computers busy for decades.

Delft University of Technology creation for Pi DaySo if you are feeling in a celebratory mood may I suggest that today, 3/14 at 1:59pm (the next three numbers in Pi) you share a piece of pie with your favorite math teacher. Perhaps you might like to bring them a Pi necklace that you made yourself.  If you’re in San Francisco stop by the Exploratorium‘s 21st annual celebration. And don’t forget wish Albert Einstein a Happy 130th Birthday; isn’t that a cool coincidence!

If you missed today’s celebration, don’t worry. You can celebrate Pi’s fraction approximation on July 22 (22/7) or the 314th day of the year on November 10th. Will the celebrating never end?

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Piece your search together with Boolify

Mar 11th, 2009 by

Question: How do you find what your looking for when searching on the Internet? Answer: Keywords, Keywords, Keywords.

It wasn’t too many years ago that teaching how to build an Internet search criteria meant explaining Boolean operators, either as words or symbols. I remember having the poster “My plump starfish quickly lowered Lincoln’s tie” to help students remember minus, plus, star (wildcard), quotes, lower case, link, and title. The acronym was an effective memory tool for the terms, but I’m not sure it was effective in showing how   combination of terms work to focus in on the sites containing the information on the student’s topic. Boolify works as both a search engine and a visual learning tool to demonstrate how Boolean operators work together.

Boolify uses the familiar mental model of building a puzzle to help students construct and organize their search criteria. Starting with a green puzzle piece a the student begins building their search with a keyword or phrase with the results appearing below with the total number of sites shown.

Boolify search query

Now Boolify becomes a powerful tool to demonstrate how to combine Boolean operators “and,” “not,” and “or’ to focus your search results.

Yellow puzzle piece representing the Boolean operator “or” placed after the green puzzle piece expands the search to locate sites with information on keyword 1 or keyword 2. Placing a blue piece, the Boolean operator “and”, focuses the search results to only those sites that have information on keyword 1 and keyword 2. If the topic is broad a red puzzle piece, the Boolean operator “not”, could be use to narrow search results by only finding sites that do not contain specific words or phrases.

Using Boolify as a whole class activity can be a very engaging way to have students work together to come up with effective search strategies. Teachers who have access to a interactive white board can engage the  entire class in brainstorming, having the students come up with suggestions on how to expand or narrow a topic. From the brainstorming activity students could then go to the board to piece together their search criteria, recording how the number of sites returned changes with each new piece added to the search query. Using Boolify in pairs or teams, students could sharpen their skills by searching for answers to trivia questions with the winning team the one who answers the question with the fewest number of sites returned.

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Posted in Boolean, literacy, search engine | No Comments »

The best of both worlds

Mar 8th, 2009 by

With the emergence of Web 2.0 tools and a greater presence of computers at all grade levels balancing tactile and digital experiences in the classroom has become a even bigger challenge. Now “cut and paste,” creativity, and  visual literacy have dual skill sets, application, and roles in student learning. How, as teachers, do we provide learning opportunities that blend the digital skills needed for the 21st century while nurturing the creative side of our students?

Here are what I think are two great examples of the blending of the best of both worlds; the tactile experience and creative ability of drawing, writing and communicating with humor, and the use of video editing software to create a short clip shared with millions via the web. Hopefully after watching the two clips your creative juices will start flowing and you may find a place where such a project might work to help your students demonstrate their knowledge of history, science, retelling a great story, or…

Thanks to Richard Byrne at Free Technology for Teachers for the introduction to Fast Talk

Here is another great example of the blending of simple drawing with clear writing to teach.

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Posted in education, literacy, mashup, publishing, technology, writing | No Comments »

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