Compressing JPEG
Using the JPEG file format for your photos is one of the most common ways to store and display digital images. However, the high quality of these images can cause them to take up a lot of space on your hard drive. If you want to save more space for your photos, you can compress them. Compressing a JPEG photo will reduce the size of the file without affecting the quality of the image.
If you want to compress your JPEG photos, the first thing you need to do is to convert them into a Y’CBCR color space. The Y’CBCR color space is similar to the color space used by digital color televisions. The Y’ component of a pixel is used to represent the brightness of the pixel. In this color space, the Cb and Cr components are also downsampled, which will improve the quality of the images.
A Y’CBCR color space also provides better compression. The Y’ component of a JPEG image is the brightness of a pixel, whereas the Cb and Cr components represent chrominance. This type of conversion increases the compression ratio, which allows for a higher perceptual quality.
Another method of compression is to use entropy coding. In entropy coding, each of the individual image components is arranged in a “zigzag” order, which results in a more compact file size. This type of encoding typically produces files that are about five percent smaller. A number of tools will let you choose the optimal level of compression, so that the end result is similar to the original.
Another way to reduce the size of your photos is to blur them. Blurred images have fewer sharp edges and more crisp details. If you blur an image, the file size will be significantly reduced, but the quality of the image will be preserved. When a JPEG photo is compressed, some of the details are lost, which can be noticeable. However, the overall color still looks recognizable.
You can also reduce the size of your JPEG files by changing the resolution and dimensions. Most standard JPEG implementations allow the user to set the compression ratio. You can select a setting from 10:1 to 100:1. However, you should consider the quality of the image you are working with. A compresser photo with a higher compression ratio will take up more space, but it will be less clear and may have more artifacts.
For the most part, JPEG images are processed at a 4:2:2 ratio, which means that the image is divided into four squares and coding is done in the upper range of the color spectrum. This is a convenient representation of the image, and it makes it easy to work with. The lower and right edge of the image can lie outside of the block boundaries, which means that it can be rotated without losing quality. However, if you want to rotate the image, the top and left edges must also be in the block boundaries. This prevents flipping the photo.
