What is JPEG ?

JPEG File format and Algorithm

 

JPEG stands for Joint Photographic Expert Group, the name of its creator.Its a file format for images or in other words an extension which you might have seen many times while dealing with your pictures as JPEG or JPG.

      In fact, it is an algorithm by most of the images are written or stored. JPEG, EXIF, JFIF and JPG are the common algorithms used by cameras, scanners and other imaging devices.The JPEG standard how an image is compressed into a stream of bytes and then decompressed  back to form an image.

   For example when a digital camera, a scanner, or any other device takes an image it first saves it as a raw image file and then converts it into a JPEG image.Usually the raw image has a size 2-6 time greater than a JPEG image, but when the raw image is processed through JPEG compression algorithms it has a low size.It can be very useful if you have a limited amount of memory.
            The JPEG image file format is almost universal.It is due to the fact that is being used in many devices, almost every imaging device, and also that it is compatible with 99% of image viewing applications and photo editing application.

         It has some advantages and disadvantages.

What actually is JPEG and its features?

 JPEG is an image format which is used to store images.It has a high compression ratio, but the compression ratio is variable.It usually achieves 10:1 ratio.The more the compression ratio is, the less will be the quality of the image.

     So if you want to experiment then open any image and save it as .png ,which is another image format with less compression.And check it's size.Then open again the original image and save it as jpeg or jpg.And note it's size, compare the sizes of both png and jpg images. Then you will learn the actual meaning of JPEG or image formats.You can also see the difference between the sizes of video files, such as a same video of same length will have less size in MP4 format than in AVI format.

  You can also try saving an image in jpg format with high compression and low compression and see the difference between their sizes and qualities.I have done that for you.

This is a JPEG image with high compression ratio.

It has a size of 17 KB.

While this JPEG image has low compression ratio.It has a size of 32.5KB.

 

 

 

Advantages of JPEG

1. It is supported by almost all image related softwares and applications that includes image viewing and photo-editing applications, as it has been used for a long time and has spread world-wide.It was introduced in 1992 and is being used widely now.
2. JPEG image files take less space which makes them ideal for storing and transferring images.
3. JPEG file format is supported by every printer, so the users don't need to change the format before printing and can directly print from image viewing application or from camera.
4. JPEG images are stored quickly by digital cameras and other imaging devices.Which has made it the default image format used by cameras and scanners so the users can take and store images quickly.

DisAdvantages of JPEG

1. While saving images as JPEG some of the data of image is lost due to high compression, that it is why it is called lossy compression method.
2. JPEG allows images to be saved consuming less space, but at the cost of quality and detail.That is why it is not good for images that are to be edited often, as some detail is lost while saving.
3. It is not good at handling line drawings.
4. Doesn't supports animation like .gif images.
5. Doesn't supports transparency.
6. Uses 8-bits for color data, with about 16.7 million colors.In contrast, modern cameras use 10 to 14 bits for colors. 

That would be all, Hope you like it!. Please leave any comments, suggestions or report any problem.

How to Change background image of Log-on Screen?

Change background image of Log-on Screen

This is the default background image of the screen what we call the Log-on screen, which is where you select user and enter password and then log-in to your account.And it is also the screen where you get the options like Lock this computer, Switch user, Log-off, Change password, and Start Task manager and others like ease of access etc, by pressing CTRL+ALT+DEL.

       In this article, I will show you how to set a custom background for log-on screen.There are various methods for doing it, but I will discuss only two best of them.One is, using a utility, for standard users.And the other is, manual method, for advanced user.

Using Tweaks Logon changer for Windows 7

This method is the easy and fast one.So lets begin.

• Download Tweaks Logon changer.
• Run it.

• Click on Change Logon Screen 
•  Select any image, and open it or double click it.

• If it asks that the image size is too large, then simply click on yes and it will adjust it.

Using manual method

 1). Locate the directory:                  C:\WINDOWS\System32\oobe\info
 2). Open it, you will see a folder named "backgrounds". If not then create one.
 3). Place any image you want to set as your logon background, but it must be a JPEG image or else it won't work.
 4). Rename that image and set its new name "backgrounddefault".
 5). Run this registry tweak. 
 6). Check to see if its working, just press ctrl+alt+delete to check.If its not working make sure that the name's spelling are correct and the image you used is JPEG.The JPEG is important.