We all utilize image compression as a daily tool, thus it’s essential. Without it, sending enormous files would take hours, we would be emailing hundreds of megabyte-sized files, our landing page would never load, and navigating the internet would feel like walking through thick mud. But being aware of how and why picture files are compressed might help us to produce correct results that accurately reflect the original intent. Here, we’ll go through the fundamental words and ideas of image compression that every designer should understand before looking at some of the more practical tools that can be of use.
Type of Compression
The following are the type of image compression available:
- Lossy Compression: Lossy removes data from the original file, ideally inconspicuously, to reduce storage requirements.
- Lossless Compression: In contrast to lossy picture compression, lossless image compression preserves all of the original data, but at a cost: the file size is frequently much larger. JPG, GIF, and MP3 are examples of lossy file formats (where information is lost), while EPS, TIF, PNG, and PSD are examples of lossless file formats (although both PNG and TIF can also be lossy).
Bitmap images can be compressed in a variety of file formats to make them smaller. Lossy methods obliterate fine details from images and color information whereas lossless methods preserve them. The following are examples of frequently used compression methods by Photoshop:
- RLE(Run Length Encoding): Run Length Encoding is referred to as RLE. It is a lossless technique that provides reasonable compression rates only for particular kinds of data. The simplest compression algorithm is probably RLE. It substitutes a count number and a single value for sequences of identical data values within a file. Some popular Windows file formats allow lossless compression.
- LZW(Lemple-Zif-Welch): Abraham Lempel, Jacob Ziv, and Terry Welch developed the table-based lookup technique known as LZW compression to compress a file into a smaller file. The TIFF image format and the GIF image format are two frequently used file formats that employ LZV compression. Text files can also be compressed using LZW compression. Supported file types include TIFF, PDF, GIF, and PostScript; lossless compression. ideally suited for pictures with huge monochromatic regions.
- CCITT: (CCITT is an acronym for International Telegraph and Telekeyed Consultive Committee, which is spelled in French.) Black and white image data in PDF files is compressed using CCITT. The data is compressed into a significantly smaller stream using Huffman encoding. A group of lossless compression methods for black-and-white images that are compatible with the PDF and PostScript file types.
- ZIP: ZIP files can hold several files using various compression methods while also supporting the storage of a file that has not been compressed at all. Because each file is saved and compressed separately, it is easier to extract them or add new ones without having to decompress or compress the entire archive. Lossless compression; PDF and TIFF file formats are compatible. Similar to LZW, ZIP compression works best with images that include substantial single-color sections.
Compressing a file in JPEG format
Photographs and other continuous-tone pictures are frequently shown in HTML documents using the Joint Photographic Experts Group (JPEG) format. JPEG preserves full-color information in an RGB image while selectively eliminating data to reduce file size. Better image quality is achieved with lower compression levels than with greater levels of compression. The Maximum quality setting typically yields results that are identical to the original.
The following steps show how to compress a file in JPEG format:
Step 1: Click File > Save As or Press Ctrl+Shift+S
Step 2: Select JPEG from the format list
Step 3: Give the file a name and location, choose how to save the file, and then click Save. Opens the JPEG Options dialogue box.
Step 4: Choose an option from the Quality menu, use the Quality slider, or input a number between 1 and 12 to specify image compression and quality.
Step 5: Pick on a format:
- Baseline (“Standard”) Employs a format familiar to the majority of web browsers.
- Baseline Optimized enhances the image’s color quality while producing a significantly reduced file size. This option is not supported by all web browsers.
- Progressive creates an image that a web browser will progressively display when it downloads it. Progressive JPEG files are not supported by all software and web browsers, are significantly larger in size, and require more RAM to display.
Step 6: Press OK
Compressing a file in PDF format
A versatile, cross-platform, and cross-application file type is a Portable Document Format (PDF). In Photoshop, there are two categories of PDF files:
- Photoshop PDF files: When Preserve Photoshop Editing Capabilities is checked in the Save Adobe PDF dialogue box, Photoshop PDF files are produced. Photoshop PDF files are limited to one image.
- Standard PDF files are those produced by other programs like Adobe Acrobat or Illustrator or when Preserve Photoshop Editing Capabilities is deselected in the Save Adobe PDF dialogue box. Pages and photos can be included in standard PDF files.
Photoshop rasterizes text and vector content while keeping pixel content when you open a typical PDF file.
The following steps show how to compress a file in PDF format:
Step 1: Click File > Save As or Press Ctrl+Shift+S.
Step 2: Select PDF from the format list
Step 3: Give the file a name and location, choose how to save the file, and then click Save.
Step 4: Choose a compression strategy in the Save Adobe PDF dialogue box.
Step 5: Select a choice from the Image Quality menu.
Step 6: Select Save PDF.