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Lesson 4 from: Mastering Your Digital Camera

Chris Weston

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Lesson Info

4. Compression

One of the major differences between JPEG and RAW is that RAW files are much larger. In this lesson, see how both JPEGs and RAW files are compressed and the pros and cons to each type.


Lesson Info


another difference between J. Pagan roars compression, which is when the camera makes the far size smaller. If I was able physically to get hold of the picture, I've just taken which, with the magic of television I can do this is what it would look like. Now. Additional file isn't a single object is made up of lots and lots of pixels, so in reality is a little bit more like a jigsaw. Jake pegs air compressed. Using what is known is a lossy algorithm. What that means is the camera takes the picture. It identifies the pixels it wants to keep on. Then it looks at the pixels that because they're all the same, such as this area of blue sky here, it could afford to throw away literally. There are fewer pixels, and that's what makes the file size smaller. The problem with lossy compression is that one says discarded pixels are thrown away. They're gone for good. So why don't your photographs have gaps in them where those pixels are missing? Well, what happens is when you open the picture in t...

he computer, the software inter plates, that missing information. Basically, what it's doing is is guessing at what should be there now. It does a pretty good job most of the time, but it is guesswork, and sometimes it guesses wrong. So your pictures don't always look as good as they can be. Raw files, on the other hand, to compress using what is known as a lossless reversible algorithm. What that means is the camera takes the picture and it rolls it up into a smaller package a little bit more quickly, and I'm doing it right now. To be fair, it doesn't for away any pixels. So when you come to view the image, the software simply unrolls it, revealing all the original data.

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Ratings and Reviews

mark jacobson

What a marvelous course! What a marvelous teacher! When I went to college, my father would always ask me about my professors, more than the courses themselves. He was passionate about learning and although too busy with earning an income to go beyond an undergrad degree, continued to read 50 books a year. I still remember how he'd get almost visibly excited when I'd tell him about some special professor who taught with such enthusiasm and, more than just passion, evident delight and joy in the subject. 'Ah they're the best, son. How wonderful you have such a teacher." Well, he passed away decades ago but if he were still around I'd get a kick out of telling him about Chris Weston, the 'Prof' of this course. He's one of the very special ones: a teacher who's loved and lived his vocation--his avocation--since he was a boy--and still is as excited about it now as he was then. The result: a course that seems to be more a labor of love--of pouring far more energy and thought into the details then one typically finds in these courses--than anything else. Bravo Chris! I'm already on to your next one.


Chris is an amazing instructor who dissects theory giving amazing analogies that bring concepts to life. I have rarely been able to sit through most video course for more than a half-hour but watched this one from beginning to end. A good refresher course if you've been away from the camera for awhile or there are some concepts that still illude you. I highly recommend this course and look forward to watching his others. Thank you for the clarity and great explanations.

Sky Bergman

This was an amazing class. I have looked at a number of basic photography classes. This one was by far the best I have seen. Chris is an exceptional teacher. He breaks things down into digestible information and then inspires you to be creative. Thank you!

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