This means trying every possible set of substitutions. Instead, it reduces the file size of a JPG, BMP, SVG or other image files. Lastly, the Text Compression Activity is an important lesson to refer back to when students start programming. Following the same heuristic might lead to different results. The text still gets compressed, no matter what. As you do so, develop a set of rules, or a âheuristicâ that generally seems to provide good results. Let's look at an example of a text message that's been compressed in a clever way. Make games, apps and art with code. Why is compression a "hard problem" for computers? Describe the purpose and rationale for lossless compression. Put students into partners or work individually. Reduce and compress Word documents (.doc, .docx, .docm, .odt) online to make them smaller, so you can better send them via email. Your friend would only be able to read it if she knew how it was encoded. In particular, when students recognize patterns that repeat, and then represent those patterns as abstract symbols, and then further recognize patterns within those patterns, it is very similar to the kinds of abstractions we develop when writing functions and procedures when programming. Explain how you would know, or why you canât know. Try to develop a general strategy that will lead to a good compression. Trade your heuristics with another group. Now you're going to get to try your hand at compressing some things on your own. It also supports unzip , allowing you to uncompress archived zip, zipx , … Since there is no way to know whatâs best, all we need is a process that comes up with some solution, and a way to make progress. Click "Zip Files". Early choices affect later ones. Free Online Automatic Text Summarization Tool. WeCompress - The Online File Compressor. "What makes doing this compression hard? Terminology: Verify students know or use an *exit ticket on this vocabulary: There is a compression algorithm called LZW compression upon which the common âzipâ utility is based. Using another groupâs heuristic, attempt to compress one or more of the poems in the tool. Explain some factors that make compression challenging. It should easily take 2 or more days of class. Why or why not. Some of these issues should surface: You can start in lots of different ways. With the same quality of work, you will be able to get the shortened document with no hassle. Yes, but itâs imprecise -- you might leave this as a lingering question that leads to the next student task. While details of LZW compression are not part of the AP course content, but the idea of, Have a large text file at the ready, such as the. Wait for the compression to … … ", "Do we think that these compression amounts that weâve found are the the best? Compression can be a "hard problem" for computers because it is difficult to know whether or not the compression you've found is optimal - if you keep trying would it get better? Give students a few minutes to decode the text. We use the best settings to maintain a good visual quality when compressing the file. Deliver or put simple instructions on the board so students can follow. (count bytes in original vs. total bytes in compressed version), Experiment with zip using text files with different contents. You may elect to not do this heuristic activity and instead get the key take-aways (see Activity Goal below) across through discussion following the previous activity. Write some examples of things you might see in a text message that are not proper English. The activity engages students in thinking and problem solving behaviors that foreshadow skills that are particularly useful for programming later down the line. the_big_bug_bit_the_bull_but_the_bull_bit_the_big_bug_back, Approximately what was the percentage of compression? Both uploaded and compressed documents are removed from our servers after a few hours. It runs locally as a browser app, thus making it much quicker than other similar zip and unzip online tools. ", "What did all groupsâ processes for compression have in common? For each poem, have the group(s) who did it figure out the best in the class, and record it on the board or somewhere that people can see. Demonstrates the use of the Text Compression Tool. Reduce file size of PDF, PowerPoint, Word, Excel, JPEG, PNG and TIFF files online. There are benefits and drawbacks to each. It also supports unzip, allowing you to uncompress archived zip, zipx, rar, tar, tar.gz, 7z, and various other archive formats. On the previous level you reconstructed the text by tracing back through the dictionary. Do you use abbreviations for common words? You just need to select the Word file (~50MB) you want to compress. encrypt data, image size reduction & watermarks, remove personal data from files, convert doc to pdf, share in the cloud and more), then you should check out. Below is a piece of text that has already been compressed, and shows some of the information about it. Is this a "good" compression rate? Warning: results may vary. This is an example of an algorithm that cannot run in a âreasonable amount of timeâ - one of the CSP learning objectives. Compare with other groups to see if you can do better. Review the teaching tips to decide which options you want to use. ), Abstraction (patterns referring to other patterns). This online image optimizer uses a smart combination of the best optimization and lossy compression algorithms to shrink JPEG and PNG images to the minimum possible size while keeping the required level of quality. Upload up to 20 images. After some experimentation students are asked to come up with a process (or algorithm) for arriving at a "good" amount of compression despite the fact that there is no way to know what is best or optimal. encrypt data, image size reduction & watermarks, remove personal data from files, convert doc to pdf, share in the cloud and more), then you should check out latest version of WinZip. There are so many possibilities itâs hard to know. Give students a minute to write, and to share with a neighbor? - Compression: Same Data, Fewer Bits. But then you might start re-thinking the dictionary to tweak some bits out. What's the point? Some online software could turn your 3 hours of the job into a task of a few minutes. The text should be a short poem (see activity recap below), The full compressed text includes BOTH the compressed text, Thus, you must account for the total number of characters in the message. Select up to 20 .jpg or .jpeg images from you device. A general "hand-wavy" understanding is all that's needed from this lesson. Please make a copy of any documents you plan to share with students. Invite responses. This is a big lesson that covers a lot of bases. There is no way to prove it or derive it beyond trying all possibilities by brute force. Have students who were assigned the same poem compare results, or seat them in the same area of the room. ", "Is there a way to know that a compressed piece of text is compressed the most possible? Activity Guide - Text Compression - Activity Guide (, Activity Guide - Text Compression Heuristics - Activity Guide (, What is the compression rate, or the compressed text size + dictionary size compared to the original text size? The groups with the best compression percentages may be asked to share their strategy with the class. Differentiation and other adjustments to this lesson. Compression is a method or protocol for using fewer bits to represent the original information. Even for small texts this will take far too long. Activity Guide - Text Compression Heuristics, Unit 2 Online Professional Learning Course, Activity Recap - Decode this Message - Activity Recap, Activity Guide - Text Compression - Activity Guide, Activity Guide - Text Compression Heuristics - Activity Guide. Students invent their own way here. You just need to select the Office file you want to compress, there is nothing to configure. Explain some factors that make compression challenging. Why do you want to compress anything? What if we need to send a large amount of text faster over the Internet, but weâve reached the physical limit of how fast we can send bits? The operation is almost always the same on every one of these free compression tools — you upload the PDF file you need to compress, select the compression settings and done, then download the compressed PDF file. Today: 146 files, 1.47GB | Total: 38,360 files, 306.47GB | From October 2019, © 2019-2020 DocuCompress | Do you want to use zip compression for real? Select all the files you wish to archive. Record your heuristic as a list of steps that someone else unfamiliar with the problem could follow and still end up with decent compression.