Is it really possible to compress information?

Compress images - this is how it works

Reducing the size of an image file can be useful for many reasons: Be it to save space on the hard drive or to enable faster downloading or uploading. Compressed images have a particularly positive effect on the Website loading times out. Because image files that are too large lead to longer loading times, which ultimately has a negative effect on the search engine ranking.

But how do you compress images with as little loss as possible, i.e. without any visible loss of image quality? And what options are available to you for this? Images can be easily scaled down online on specially set up websites. But you also have numerous options offline. We offer you an overview of the subject of image compression.

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Why should I compress my pictures?

Images and photos in high resolution are no longer uncommon. The number of pixels in digital photographs is increasing, and so is the number of pixels Size of the image files. But regardless of whether you use images for your website or want to send them by e-mail, you should pay attention to the file size. Because the smaller the files used, the faster they will be transferred, which is particularly advantageous for two reasons:

  • A quick loading process increases visitor satisfaction (especially those of users with mobile internet access).
  • Fast loading times have a positive effect on that Ranking on search engines out.

The right file format for images on the web

Before you post images on your website, you should check the format of the image files. Not every graphic format is suitable for use on the Internet. These three file formats are particularly suitable for use on the Internet:

  • JPG / JPEG: The JPG format is one of the most widely used digital image formats. It can display up to 16.7 million colors and is highly compressed (lossy). JPGs are particularly suitable for storing photos or photo-like graphics - especially those with many different colors and strong contrasts.
  • PNG: The PNG format can display 256 (PNG8) to 16.7 million (PNG24) colors and is also used very often on the Internet. In contrast to JPGs, it can be compressed with almost no loss. PNG files are ideal for storing graphics, logos and texts. Images that only use a few colors can be compressed as PNGs to a fraction of the original size.
  • GIF: Even GIF files - although they can only display 256 colors - are used relatively frequently on the Internet. This is mainly due to the fact that the GIF format can be used to display small animations of images in a row, which are very popular in social media and the like.

The compression of photos and images is one of the most important steps to improve the performance of your own web project. However, there are other ways to optimize the image material used: For example, it is worthwhile to use the Specify dimensions of an image in the source codeso that the browser does not have to calculate it itself. That too Remove metadata (Meta tags, EXIF ​​information, etc.) has a positive effect on the loading speed. If your web application contains a large number of images, the delivery recommended via a content delivery network (CDN).

Compress images: the best solutions at a glance

Pixelated images on websites look unprofessional and are therefore a no-go. A high image quality, on the other hand, requires a lot of data volume and thus lengthens the loading process of a website. Current image compression programs therefore keep the loss of quality so low that it is often invisible to the naked eye. Professional photo editing programs such as Photoshop have been offering corresponding functions for a long time. But there are also numerous freeOffline and online applicationswhich also know how to convince through their functions and their ease of use.

Compress images online

If you want to compress photos without having to install special software, you can also easily optimize your photos directly online. Exist for this purpose various offers on the webthat allow you to compress it for free. The tools usually differ in the available file formats, the possible Degrees of compression and often have limitations with regard to the number of possible compressions. You can find some of the best solutions in the following sections.


The online tool Optimizilla from Mediafox Marketing enables up to 20 pictures at the same time upload and then compress. The prerequisite is that the images are either in JPEG or PNG format. The web application uses a Combination of different compression algorithms which are characterized by a good ratio of compression and image quality. You can use the slider to control the Specify the compression levelbefore you download the results individually or as a group as a ZIP file.

So that you can find the best possible settings, Optimizilla supports you through Thumbnails of the original and its compressed counterpart. In addition, the tool indicates the respective file size. All uploaded images are automatically deleted from the provider's servers after one hour.

advantages disadvantage
Compression level adjustable Limit of 20 simultaneous compressions
Miniature preview of the original and the result  


TinyPNG allows - contrary to what its name suggests - not only the compression of PNG, but also of JPEG files. In the free standard version you can up to 20 images Optimize these two formats at the same time, whereby the maximum file size per image is limited to 5 megabytes.

The tool from voormedia has one predefined compression levelwhich cannot be adjusted, but reduces the image size by up to 86 percent. You drag the photos you want via Drag and drop in the designated area and then download the results in JPEG or PNG format or as a ZIP file. Alternatively, it can be uploaded to the Dropbox cloud storage service.

advantages disadvantage
Results can be uploaded to Dropbox Limit to 20 simultaneous compressions and 5 megabytes of file size (in the standard edition)
  Compression level cannot be adjusted


ILoveIMG is a whole Online suite from useful image editing tools. The Barcelona-based development team provides, among other things. Applications available to deal with Crop, scale, convert images and also compress to let. For the latter, select the "Compress image" button and then insert the desired image material using drag-and-drop or the file browser. Possible formats are JPEG, PNG and GIF.

While iLoveIMG only has a single, predefined compression mode, the tool provides several different export options: not only can the results be downloaded to the local hard drive, but also uploaded to Google Drive and Dropbox as well as the Passing on a download link to the compressed images. If you are not satisfied with the compression result, you can simply delete it by clicking on the trash can symbol.

advantages disadvantage
The results can be uploaded to Google Drive and Dropbox only one compression mode
further tools for cropping, scaling and converting available no preview function

Compress images with Photoshop

Of course, you can also compress your images with professional image editing programs. Above all, Photoshop should be mentioned here as the industry leader. In addition to its functions for the creative design and optimization of photo material, the Adobe tool offers various options for changing the image format and the Adjust image size. The option "Save for web“, Which Adobe implemented especially for the purpose of optimized photos and images for homepages and co. In this mode, compression is not limited to the three important web formats GIF, PNG and JPEG, but also the one geared towards mobile devices Raster graphic format WBMP (Wireless Bitmap) available.

Once you have a picture in Photoshop web optimization mode edit, a new window opens in which you can not only set the specified target formats, but also the desired photo Color depth and dimensions can optimize for your website. In the preview window, the Adobe tool compares the original and the target image (including absolute information on the file size) so that you can easily see how strong each is Compression steps affect quality.

advantages disadvantage
Live preview for up to three compression results very computationally intensive
various image processing features available high costs

Compress images using freeware and open source programs

Photoshop shows how convenient it is to compress photos with Desktop applications is. By default, these not only offer significantly more functions, but also have the advantage over web tools that they can be used without an existing internet connection. If you downsize the images of your website, however, it does not necessarily have to be a premium solution like Adobe's hobbyhorse or another paid alternative. Are you at one tight budget bound or not interested in more complex editing features, you can already achieve first-class optimization results in terms of photos, images, etc. with a freeware or open source program. But which of the numerous free tools available are really recommended?


Since 1996, the image viewing program IrfanView has been one of the most popular freeware solutions for Windows PCs - according to the manufacturer the monthly download numbers ata million on average. This is mainly due to the attractive license model of the tool: While private use is completely free, you have to purchase a license for a low double-digit amount (one-time payment) for commercial use.

By default, the image viewer supports numerous image formats such as PNG, JPEG, GIF, BMP and much more m. Once an image has been inserted, it can be converted into these formats at any time. When it comes to compressing images specifically for the web, however, the plug-in function "Save for the web" to recommend. Thanks to this extension, you can optimize batches of images and photos, using the slider to set how much Original image quality should be preserved. A preview image and the compressed file size give you an insight into the expected end result.

advantages disadvantage
Batch processing possible Compression plug-in only offers an English-language interface
Preview function and adjustable compression level  


When looking for Photoshop alternatives from the open source sector, one inevitably comes across GIMP (GNU I.stomach M.manipulation Program). The graphics program for Linux, macOS and Windows, released in 1998, has been convincing for years with its Functionalitywhich is strongly reminiscent of the commercial model from Adobe. It now supports more than thirty file formats - including those that are crucial for the web GIF, JPEG and PNG. You can convert your image files to one of these web formats at any time using the GIMP software.

However, in addition to converting images to a smaller file format with the GIMP, you also have advanced export options at hand, which you can only use to compress an image. Use the slider to set how strong the Compression level should be. The extended options are also practical: if you activate the “Progressive” property, for example, the result is slightly larger - the individual ones Areas will however loaded in a specific orderso that a rough view of the overall picture can be displayed after a short loading time.

advantages disadvantage
Open source Preview only shows the file size of the result
Compression level adjustable  


The freeware program PNGGauntlet provides one Graphical user interface (English) for the three open source tools PNGOUT, OptiPNG and DeflOpt, all of which are for the Optimization and compression of image material in PNG format were developed. The application, which is only available for Windows, is therefore the perfect solution for creating particularly small logos, graphics and lettering in PNG format for your web project. The output formats for the compression and conversion process are - in addition to PNG yourself - too JPEG, GIF, TIFF and BMP possible.

You have two options for compressing your photos with PNGGauntlet: You access the Standard set-up by inserting an image or several images and then directly pressing "Optimize!", or you can choose first an individual set-upby adjusting the settings of the three implemented tools using the button of the same name. Regardless of the method chosen, the freeware tool will show you the new size of the image file (s) and the opposite of the original saved file size in percent.

advantages disadvantage
uncomplicated batch processing no preview mode
Individualization of the degree of compression possible Limitation to PNG as output format


If you want to compress the images and photos of your web project and a Open source tool for macOS ImageOptim developed by Kornel Lesinski is recommended. The GPL-licensed program combines a handful of image optimization tools, e.g. B. MozJPEG, pngquant and SVGO, and in this way not only enables the removal of unimportant ones EXIF metadata, but also the general one Compression of image and photo material of various kinds (JPEG, SVG, GIF, PNG).

By Drag and drop the desired image files can be inserted into ImageOptim, whereupon the program starts immediately with the compression. However, you can make changes to the settings at any time and the Adjust the compression strength or add or deselect options. Then just click on "Repeat" to carry out the conversion again.

advantages disadvantage
various compression functions no preview mode
Open source  
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