Image compression is a process of minimizing the size of an image in bytes without hindering its quality to a significant level. By reducing the size of the file, it allows users to get more memory or disk space in order to store more files.
Additionally, it also reduces the time it takes for images to be transmitted over the internet. In this article, we will be learning everything about image compression.
How Does Image Compression Work?
Whether you want to know how to compress PNG or JPEG, you can get the answer easily when you understand how images are compressed in the first place.
Effectively using image compression can make a significant difference in the size and appearance of the image files. In simple terms, image compression works to reduce the size of the file by taking out information that is not important.
In an image compression method, you do not have to lose any data within the file to compress it. Choosing the right type of compression method can ensure that the image looks as good as it could after reducing the size. Below are the two types of methods through which images are compressed.
Lossy and Lossless Compression – What are they and How the Two Methods Differ From One Another?
When it comes to choosing the right method of compression, people commonly rely on lossless compression. Although the approach is beneficial for many images, there are many images that might not be compatible with this approach.
Lossless image compression implies that all the data included in the original file is transferred to the compressed file. And, Lossy compression removes the data that is not important to reduce the file size.
Basically, it is up to the users how much data they want to save while compressing the image. Let’s understand bot the format more comprehensively.
Lossy Compression
There various methods to reduce the size of the file using the Lossy compression method. In some methods, you can combine the Lossy compression method with lossless compression to create smaller file sizes.
One way is to reduce the color space of the image by choosing only the most common colors of the image. This is typically used in GIF and at times in PNG images to reduce the file size. When this method is used on the right type of images along with dithering, it can ensure that the results are identical to the original form.
JPEG images use Transform encoding, which average out the color in small segments of the block from the image by leveraging discrete cosine transform or DCT while maintaining adequate brightness information.
Chroma subsampling is a method of Lossy compression that works on a perception that humans notice changes in brightness more than changes in color.
Therefore, it changes the average chroma information while ensuring adequate luma information. This method is used in JPEG images as well as video encoding schemes.
Lossless Compression
Similar to Lossy compression, there are several methods’ to execute Lossless compression as well. There is a common Run-Length Encoding method, which elements with similar values and stores them in a single count and value.
It is ideal for simple graphic files that already contain a series of identical data elements. PNG images typically use DEFLATED lossless data compression method. It combines Huffman coding and the LZ77 algorithm to compress the file.
Finally, Lempel-Ziv-Welch is a lossless compression method that runs limited data analysis. This algorithm is used in TIFF and GIF file formats.
What are the Different Types of Image Files?
While there are different types of image files, there are three types of image files that are most commonly used. Below we will be discussing these three image files in detail –
PNG
PNG, also known as Portable Network Graphics, is an image format that leverages lossless data compression and is designed to replace the GIF format. PNG, for a long time, was unsupported by Internet Explorer, which makes it less common as opposed to JPEG and GIF formats.
However, PNG presently supports all major browsers. This file format support palette-based color, RGBA, and RGB color spaces, and grayscale. One of the prominent benefits of PNG is that it is compatible with an array of transparency options.
JPEG
Joint Photographic Experts Group or JPEG is a popular image format that leverages Lossy compression in order to design small file sizes. JPEG allows users to fine-tune the compression quantity they wish to use.
So if used correctly, it allows users to have better quality images while reasonably reducing the file size.
Considering that JPEG images use Lossy compression, the image saved in it are vulnerable to artifacting where you can see strange halos and pixelization across a certain part of the image.
This is especially evident in areas where there is high contrast between colors. Typically, the higher the contrast in the image, the higher should be the focus on preserving the quality of the image in order to get a decent looking outcome.
GIF
GIF is the abbreviation for Graphics Interchange Format and is a type of bitmap image format that was coined by CompuServe in the year 1987. The format supports around 8 bits per pixel, which means that an image can be up to 256 unique RGB colors. One of the prominent benefits of GIF format is that it facilitates animated images, which is something that either of the above formats supports.
Final Thoughts
Each of the formats is used for different forms of images. Choosing the right format and compressing approach will allow users to get higher quality images while reducing the size. Compressing images come with an array of benefits and are used for different purposes.
It allows users to save more storage space so that they save more files. It also makes it easier for users to share the files over the web as well as different devices. A right image compressor allows you to reduce the image without hindering its quality.
