image-compression

What is the cause/use/reason for the blocks that show up in high compression videos?

Be patient since I haven't worked with compression algorithms much so this may be obvious to some of you. Something I've always noticed when some streaming video starts to lag. I only realized I was curious when looking over this question: http://stackoverflow.com/questions/891643/twitter-image-encoding-challenge/929360#929360 I'm not ...

Is it possible to tell the quality level of a JPEG?

This is really a two part question, since I don't fully understand how these things work just yet: My situation: I'm writing a web app which lets the user upload an image. My app then resizes to something displayable (eg: 640x480-ish) and saves the file for use later. My questions: Given an arbitrary JPEG file, is it possible to tell...

On-the-fly lossless image compression

I have an embedded application where an image scanner sends out a stream of 16-bit pixels that are later assembled to a grayscale image. As I need to both save this data locally and forward it to a network interface, I'd like to compress the data stream to reduce the required storage space and network bandwidth. Is there a simple algori...

Code Golf: 1x1 black pixel

Recently, I used my favorite image editor to make a 1x1 black pixel (which can come in handy when you want to draw solid boxes in HTML cheaply). Even though I made it a monochrome PNG, it came out to be 120 bytes! I mean, that's kind of steep. 120 bytes. For one pixel. I then converted it to a GIF, which dropped the size down to 43 ...

Image compression before upload - facebook

Hi, I am developing a java web site that demands saving user info with their images. Now the images could be shown in varying sizes e.g. 40px by 40px on one page, where as say 120px by 120px on another. How can i maintain a good quality of pictures irrespective of its display size. Doesn't it happen in facebook? I want it same way. Plea...