You don’t have to look too far when searching for free stock photos and images on the internet. But just because images are free, doesn’t automatically mean that they’re all completely unrestricted for use. This is where special licences come into play. We’ll guide you through an overview of the best sources for licence-free images available online.
Most users know common picture formats such as JPG and PNG. However, their exact differences and advantages of the different formats aren’t well known. It’s often difficult or impossible to tell the difference between a JPG file and a PNG or GIF file. But a closer look at the different image formats is worthwhile. Each format has advantages and disadvantages and is designed for different areas of application. We’ll show the most common image file formats (pixel and vector graphics) and explain when you should choose which format.
- Which image file formats exist?
- Choosing the right image file format
- An overview of the most important pixel formats
- An overview of the most important vector formats
Which image file formats exist?
Before we go into detail on which image file formats exist, it’s worth understanding the basic differences between pixel, raster, and vector graphics.
As the name already suggests, pixel graphics consist of pixels. What exactly does this mean? Pixels are individual dots that make up a picture or graphic. The larger the number of pixels in an image, the higher the resolution and file size. The disadvantage of pixel graphics is that scaling the image is associated with a loss of quality. Each pixel has a defined size. If you enlarge a file, the pixels are also stretched and the quality decreases.
Always save pixel graphics in the exact size to fit the platform you’re going to need it for. In this way, you’ll avoid any loss of quality when you increase the image size later on.
Vector-based graphics don’t have this disadvantage. These image file formats have an image composed of two-dimensional objects that define the position, dimensions, and colours of the image. This allows vector graphics to be scaled flexibly while maintaining constant quality. Picture formats in this category are suitable for graphics that are used in different sizes, typically logos or other marketing materials.
Make sure you always receive the master file of an image before passing it on to an external source as a graphic design task. This way, you’ll be able to protect your images properly while being able to save the file in any given size.
Choosing the right image file format
Choosing the right image file type largely depends on how you’re going to use the image. The following factors influence the file format choice:
- Do you need the image in different sizes?
- Are you using image formats for web or print?
- What file size do you need the image in and how important is a high image quality?
- Does the image require many different shades of colour?
For web purposes, quality comes in second place. What’s more important is a small file size and a short loading time. Accordingly, lossy compression is often acceptable. In this case, the process leads to a loss of quality because data is removed from the image or reduced to one pixel. With lossless compression, on the other hand, the quality is maintained even with a reduced file size. When compressing images, pixels of the same colour category are grouped together and metadata is removed.
More information on Google’s WebP-Format – which is characterised among other things by a particularly efficient compression – is also available in the Digital Guide.
An overview of the most important pixel formats
JPG, PNG, or GIF: Some of the best-known image file formats are pixel formats. The reason: Raster graphics are suitable for almost all areas of application and can be opened and edited independently of which program you use. In addition, the usually detailed colour gradations and complex colour gradients are ideal for presenting photographs in the best light. The lossless compression also lends itself perfectly to the presentation of detailed graphics on the web. Below, we’ll introduce you to the most common pixel formats as well as their advantages and disadvantages:
GIF: Graphics Interchange Format
Have you ever noticed animated advertising banners on a website or moving pictures in your Facebook feed? These were probably GIFs. GIFs are characterised by their animated nature. A single GIF file contains all frames and time information needed for an animation.
This image file format consists of up to 256 colours in the RGB colour space and is therefore not suitable for colourful and complex photos that normally cover several thousand colours. At the same time, the limited choice of colours is an advantage if you’re using image formats for web, because the reduced file size means shorter loading times – even with animated files. Sharp edges of shapes or fonts are even better represented in the GIF format than as a JPG image. This image file type is therefore ideal for small graphic elements and for web graphics.
|Lossless compression||Limited choice of colours|
|Animations are possible||Not well suited for photography with a broad range of colours|
|Small file size||Flat image format|
|Short loading time|
PNG: Portable Network Graphics
The PNG image file format was developed as an advanced alternative to GIFs. Unlike a GIF, a PNG can be saved with a transparent or semi-transparent background and supports the alpha channel. In addition, the PNG format adapts to optimised computers, meaning that it adjusts itself to a growing range of colours. The colour spectrum covers up to 16 million colours, which is significantly more than a GIF. However, this image format is not suitable for printing because PNGs do not support the CMYK colour model. This is where the name ‘Portable Network Graphics’ comes from, which implies the primarily digital use.
Although their choice of colours is limited, the GIF image format is still being used a lot, since animations aren’t possible with the PNG alternative.
PNG is a typical image format for the web that is characterised by lossless compression. Even small files are able to retain their high quality and resolution and show fine nuances. Accordingly, PNGs are suitable for logos or other small images with many shades, making them ideal for further processing and for saving in different sizes. However, this also means that they require more memory space. A PNG file is up to ten times larger than a comparable JPG.
|Lossless compressions||Not suitable for print|
|Supports (semi)-transparency and the alpha channel||Requires more memory space|
|Full colour spectrum||Not universally supported|
|Animations are not possible|
JPG/JPEG: Joint Photographic Experts Group
The JPG format is the most commonly used image file format. The files are characterised by high compatibility and universal application possibilities. This format can be opened and converted with almost any application. In addition, JPGs offer the full colour spectrum with up to 16 million colours. The disadvantage is that compression of an image file leads to the loss of image data due to the combination of similar pixels, which in turn leads to a loss of quality. This is also the main difference between JPG files and the PNG format.
JPG vs. PNG: Both image file types are very common for web images, but are actually quite different. Choosing the right image format will depend on its intended use.
For web use, the quality of a JPG file is sufficient in many cases, and lets you benefit from a fast loading time thanks to the small file size. So-called progressive JPEGs offer an additional advantage in terms of the user experience, as images are loaded pixel by pixel, so that unwanted white areas are avoided on websites. A JPG can also be sent quickly and easily by email as a preview. Without compression, high-quality JPG files are also suitable for printing.
Always choose the best possible combination of quality and file size when working with image formats for web.
|High compatibility||Lossy compression|
|Widespread use||Doesn’t support transparencies and animations|
|Quick loading time||No layers|
|Full colour spectrum|
TIFF: Tagged Image File Format
The TIFF format differs significantly from other image file formats presented so far. Most web browsers do not support this format, which makes it unsuitable for images displayed on the web. However, TIFF offers significant advantages when it comes to editing images. The format supports both RGB and CMYK colour models and has a high colour depth of up to 32 bits per colour component. In addition, layers, masks, and transparencies can be saved.
Lossless compression allows you to store or copy files without any loss of quality. The TIFF format is therefore ideal for printing high quality images. Image information is either not compressed at all or compressed without any loss of data. However, the high-quality means that images require more storage space. This property also virtually rules out the use of image formats for web.
|Lossless compression||Not compatible with many browsers|
|High image quality||Requires more storage space|
|Ideal for photograph printouts|
|Transparencies and layers|
BMP: Windows bitmap
Since 1990, the BMP image file format has been an integral part of the Microsoft operating system and Windows 3.0. Accordingly, BMPs can be opened without additional plug-ins or third-party programs. Although this image format has now been largely replaced by other formats, it is still in use.
BMP is a simply structured image format that is characterised by fast processing times. Even after lossless compression, image data is still relatively large because all pixels are stored with their respective colour values. Today, there are other image file formats with which an equally loss-free compression is achieved alongside by a smaller file size. In the age of communication via email and web platforms, this image format is therefore becoming increasingly uninteresting and unsuitable for modern applications.
|An integral part of Windows||Big file outputs even after compression|
|Large colour spectrum|
PSD: Photoshop Document
PSD is the format of the leading image editing program Adobe Photoshop and a format frequently used by graphic designers. However, editing requires the appropriate software. Therefore, the PSD format is often unsuitable for individuals and for collaborative work. You can work around this problem by using Adobe Photoshop and converting the file to another image file type. Conversion is also necessary before printing.
With the PSD format, each image consists of several layers that can be easily edited. In principle, these files are raster graphics, but they can also contain vector graphics. This image file format is therefore ideal for extensive image editing.
Adobe Photoshop is available as part of the Adobe Creative Cloud at a cost. Free Photoshop alternatives are gaining in popularity these days, as many of them boast a similar spectrum of features.
|Extensive editing of image layers||Photoshop is a prerequisite|
|Creation of videos and animations possible||Large storage capacity due to layers|
|Raster and vector graphics|
|Conversion to other formats possible|
An overview of the most important vector formats
In contrast to pixel graphics, which are fixed in size, vector graphics are much more flexible and therefore ideal for displaying geometric shapes and fonts. Lossless scaling also makes it easier to create responsive web elements. In most cases, special graphics programs are required for processing these files. Therefore, the following image file formats are usually exclusively used by graphic designers. But individuals are increasingly also taking a liking to the easily adaptable vector graphics thanks to free software alternatives.
PDF: Portable Document Format
The PDF image file format is developed by Adobe, but, unlike other Adobe formats, does not require any company-specific software (although Acrobat Reader is the corresponding standard). The PDF format has established itself as a reliable exchange format and can be viewed without paid editing software – on any device, any operating system, and any web browser. The format is particularly popular to showcase print files.
With the Adobe range of programs, which are subject to a fee, PDFs can be processed in a versatile and flexible way. The foundation of this picture format particularly shows its strength for vector graphics, but also maps pixel graphics. Even in the free version, PDFs can be expanded on with additional features such as notes, comments, or file attachments. Appropriate security settings can be used to prevent editing by third parties.
|High compatibility, independent of platform||Editing only possible with payed version|
|No chargeable software necessary||Text is recognized as images|
|The standard for print files||Often high storage space required|
AI: Adobe Illustrator format
Like the PDF format, the AI format is a native image format of the Adobe family. However, unlike PDF, you need the Adobe Illustrator program to display these files. The vector-based format can be scaled flexibly and offers the possibility to embed or link raster graphics. The image file format is mostly used to save logos and other marketing materials, which are required in different sizes.
With Adobe Illustrator, files can also be saved in any other common image file format. This facilitates the exchange of files between graphic designers and private individuals. Another advantage is that you can save multiple variations in a single file by hiding and unhiding layers.
Among professional graphic designers this image file format has established itself as the industry standard.
|Highly scalable||Requires plenty of storage space|
|Multiple layers||Adobe Illustrator is a prerequisite|
|Compatible with other Adobe programs|
EPS: Encapsulated PostScript
In 1987, Adobe published the EPS format in the PostScript programming language. Today, the image format has largely been replaced by the more widely used PDF, which is also based on PostScript.
EPS was the first format that made it possible to display documents exactly as they appear in print. EPS files, like PDFs, can be opened with free software across all platforms. The most common program to open EPS files is Adobe Acrobat Reader, but there is a wide range of alternatives available. The lossless format integrates pixel and vector graphics and is characterised by a particularly high degree of adaptability and scalability. One of the disadvantages is that EPS files are limited to one document page and do not distinguish between vector and bitmap.
|High quality images suited for print||Replaced by PDF files|
|Compatible with almost every design software||Limited to one page|
|Doesn’t distinguish between vector and bitmap|
SVG: Scalable Vector Graphics
The XML-based vector format SVG appeared in 1999 and shows images and their elements in text format. Since not all users, especially individuals, have access to Adobe Creative Suite, AI files are sometimes unsuitable for sharing. SVG graphics, on the other hand, are ideal for sending vector graphics, as they don’t require any specific software. In theory, the vector format can be created in a simple text editor, but this isn’t common practice.
In the Adobe Creative Cloud, SVG graphics can only be opened with Adobe Illustrator. To edit them in InDesign or Photoshop, a conversion to the EPS format is necessary.
The SVG image file format has been around for over 20 years. It is experiencing a boom due to the increasing variety of screen sizes and its responsive design. SVG graphics are rescaled with every screen layout. Accordingly, the files are always displayed in maximum sharpness and make it much easier to set up a responsive design. The World Wide Web Consortium (W3C) also standardised the format in 2001 and recommends SVG for displaying two-dimensional vector graphics on the web.
|Supported by most web browsers||More complex and detailed graphics increase the file size considerably|
|Lossless scaling||Not compatible with certain browsers|
|Responsive design||Only editable with Illustrator within Adobe Creative Cloud|
|Small file size|