JPEG is one of the most commonly used standards for compressing images and photographs. It works particularly well for big, complex pictures where there are a lot of gradients. It’s not ideal for images with solid lines or text. Like any standard, it has benefits and drawbacks.
History of JPEG
JPEG is named for the professional group that developed it, Joint Photographic Expert Group. The group established the standard in 1986. Photographers used it first. But as people created the Internet and related technologies, others needed smaller image files, too. These individuals began applying the JPG standard outside of photography. Today, people use JPEG in everything from creating business documents to interacting on social media.
Major JPEG Categories
There are two major categories of JPEG image compression.
- JPEG/Exif (Exchangeable Image File Format)–Used by digital cameras to capture and store pictures
- JPEG/JFIF (JPEG File Interchange Format)–Used for image transferring and storing, especially over the Internet
Many people don’t distinguish between the two JPEG types. They will refer to both JPEG/Exif and JPEG/JFIF simply as JPEG.
Advantages of JPEG Image Format
There are several advantages of JPEG image format:
- JPEG format has been in use for a long time and is extremely portable;
- JPEG format is compatible with almost every image processing application;
- JPEG format is compatible with most of the hardware devices e.g printers etc – therefore it is very easy to print the images in JPEG format;
- JPEG format can be used to store high-resolution fast-moving images which would be a blur in other image formats because owing to their small size, JPEG images can be stored quickly from a camera to storage device;
- Size of JPEG images can be reduced and compressed which makes this file format suitable for transferring images over the internet because it consumes less bandwidth. A JPEG image can be compressed down to 5% of its original size.
There are plenty of advantages of JPEG Image format; however, there are certain disadvantages and drawbacks of these images as well which are of major concern for the photographers and computer scientist which cannot be neglected.
JPEG Compression Methods
JPG compression manipulates the fact that the eye is more sensitive to brightness than to color. It eliminates the colors at the highest frequencies. You have trouble seeing these, anyway, so you don’t miss them. You might not even be able to pick out which image is JPEG in a comparison.
Understanding this concept, you can create a JPEG image with more than one JPEG compression technique. JPG compression steps thus can vary. But the three most popular techniques include
- Downsampling the chrominance channels (tweaking the red and blue color differences)
- Quantization of the discrete cosine transformation
- Entropy coding
Each of these methods involves creating matrices via image compression algorithms. But only entropy coding is lossless JPEG compression.
Why JPEG Compression Is Necessary
If you compress image file size with the JPEG standard, the file doesn’t take up as much space. In fact, JPEG lets you compress picture file size down to 5 percent of its original size. That means you can keep more files in your storage. This is important for any tech user. But it is especially handy for webmasters or designers to compress an image file online or offline. If they compress photos for the web, they can make sites that have more pictures and are nicer to view. That has a heavy influence on site traffic. If a web host happens to transfer data slowly, the compression can help you see the full website page and interact with it faster.
Additionally, some devices create bottlenecks. They can read the data just fine. But they are set up to read the information at slower rates. If you compress photo file size, the slower device can load the picture faster.
With the above in mind, you might find JPEG image compression useful in situations such as
- Emailing a photo to a friend
- Sending an image document to a colleague during a webinar
- Creating a PDF file
- Posting an article on your blog
- Viewing a website on an older laptop, smartphone or laptop
The bottom line is, when you compress a JPEG picture, both speed and economy improve. We are conditioned to want technology to move quickly and inexpensively. So JPEG image compression techniques can help the overall user experience.
Disadvantages of JPEG Image Compression
- JPEG compression technique is a lossy compression. Lossy compression means that after the image is compressed in JPEG format, it loses certain actual contents of the image;
- Quality of Image is reduced after JPEG compression owing to the loss of actual content of the image.
JPEG image compression is not suitable for images with sharp edges and lines. JPEG image format is not capable of handling animated graphic images;
- JPEG images do not support layered images. The graphic designer needs to work on layered images in order to manipulate and edit graphic images which are not possible with JPEG Images;
- Only 8-bit images are supported by JPEG format. On the other hand, modern high-resolution digital cameras support 10, 12, 14 or 16-bit images. If these images are stored in JPEG format, extra information is discarded, resulting in decreased image quality.
JPEG Compression for Barcodes and Facial Images
As discussed, JPEG compression results in loss of data. JPEG compression should not be used to store barcodes. Storing barcodes in JPEG format can result in distorted barcode pattern and can add noise to the barcode image which makes it very difficult for barcode scanners to decode the actual contents of the barcode. Similarly, JPEG compression is not suitable for storing facial. It can make it difficult for face recognition software to recognize facial images compressed with JPEG compression technique.
How to compress JPEG for web and other projects
You can use a JPEG compression program to compress a picture file offline. But there are many Internet-based tools to compress JPEG file size online for free, too. If you’re working offline, you generally just make sure that the image is selected. Then select the degree to which you want to compress image size, such as 75 percent. (The default is 65 percent, as it eliminates a decent amount of data without sacrificing too much quality.) Some tools allow you to select options that will optimize the compression for different purposes, too. For example, you could compress images for web pages. Alternately, you could compress for an email message. You also might have the option to compress multiple images at once.
The best JPEG compression tools will give you information about the new JPEG file. For example, a tool can estimate how small the new file will be. It also might let you know the pixel dimensions or let you see the effects of the compression in advance. So, you can have a sense of whether the file will work for you.
It can be concluded from aforementioned facts that JPEG images should only be used in case you want small sized, portable images with smooth edges and color contrast, irrespective of the image quality; however if you want high-resolution editable images with sharp contrast, using JPEG image is not a good choice and other image formats such PNG and GIF should be considered which are based on lossless compression algorithms.