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WHY CARE ABOUT THE DIGITAL QUALITY OF AN IMAGE?
Ship in a bottle.
(Why purchase an image that only provides half of what you need when you can have an image that works for every aspect of your end product?)
How can you be sure that the image you purchase will work perfectly for its intended use? Here Maria Stranger, Retoucher and Image Quality Specialist, explains the concept.

The motif is the first thing that attracts you

The motif bears a lot of meaning, it's the first thing that attracts you. It is important that the image exudes what you want to say, the message you want to convey. To be able to deliver your message through images, as best as possible and without any doubt as to what you want to say, the image's technological quality must be just as high as the quality of the motif.

RGB, pixels...say what?

A digital image is made up of image points (pixels, abbreviated as px), much like the grain in film. On a computer, the light value of every pixel is represented by a code of ones and zeroes. The size of an image is stated in pixels.

An image's digital size (file size) is measured in kilobytes (kB), megabytes (MB) or gigabytes (GB).

The bit depth (also known as pixel depth or color depth) indicates how much information there is about the color in every pixel on the image. The more bits per pixel, the more available colors there are and the more exact the color rendering.

There are two ways of looking at colors; RGB for on-screen images and CMYK for print images. RGB images consist of three color channels - red, green and blue. An RGB image with eight bits per pixel has 256 possible values for every channel, which results in more than 16 million possible color values. RGB images with eight bits per channel (BCP) are sometimes called 24-bit images (8 bits × 3 channels = 24 data bits per pixel).

Digital quality is about size and resolution

To be able to use images in different end-products such as in print, in web pages, on iPads, in slide shows, etc., requires a variety of conversions and adjustments. An image's color spaces, resolution, sharpness, etc., must be adjusted in order to achieve the best possible quality, and convey the right message.

There is no point in using a larger image than what is necessary for the end-product. The image will not look better - it will only be heavier and take up more data space. Using the size that is needed is best. Never use a smaller size as the image will only look pixelated.

The resolution and size of an image are important. These are area of constant development. Computer screens are becoming better and images can be shown in more detail, which places more demand on your images to have high technological quality.

When you want to use an image on a website, you only need to be interested in how many pixels it should have, its height and width. Resolution is only interesting when the image is to be used in a physical form, i.e. when it will be printed out.

In the past, people used the abbreviation dpi (dots per inch) to describe the resolution of an image and other units. Nowadays we use dpi when talking about the resolution of a printer. And when we talk about digital images we use ppi (pixels per inch) instead.

The size of an image is also affected by the motif

When you choose images for web usage, besides size, it is also important that you think about the contents of the motif. Small images with lots of detail and lines can make the image feel gritty and the motif will be harder to understand.

Simpler and clearer contents make it easier for the viewer to understand the message. When working with an image for a website, from time to time it's a good idea to apply the helicopter perspective and look at the website as a whole.

If you are printing an image, bear in mind that the motif can play a vital role in what resolution you need. An image that has many details in it requires a higher resolution but an image with fewer details can be printed with a lower resolution. Large images, banners for facades, for example, do not need to be printed in high resolution because you can't see the image from close up anyway. If you are going to print an image, the resolution has to be adjusted. And different types of printing require different resolutions. Images should be adjusted to the different types of breaks, the density of the grid, type of paper, coated or uncoated paper, etc.
The right color space
Another thing that is important is to have the right color space. The eye sees colors in its own way but a screen will display colors in RGB. In order for printing technology to do justice to your image, it must be in the CMYK color model for four-color printing.

You can then create an ICC profile (a character curve) for a specific printer, or for the screen on which your image will be displayed. This way, the image can be adjusted to exactly how you want it.

Compare light and color areas for additional nuances

Besides these different adjustments, it is also important that the image is complete. In image processing programs, it is very easy to make an image lighter or darker.
A photograph that has been taken in the evening light and then brightened up too much on a computer may have problems with the shadows, where exposure isn't very good.

Be sure to ensure that the register of midtones - that is, all the colors and nuances between black and white that your image contains - is kept so that there is as much information, as many nuances, as possible in the image. When midtones transfer into highlights (bright parts) and shadows (dark parts), it is important that the image has as many nuances (or tones) as possible so that hard edges, or straight blacks or whites, don't occur.

Check the image at 100%

Pace through and check the image at 100% its size, so that you can touch up and take away dust on the sensor, etc. Dust can be clearly seen as soft, darker round spots on large single-colored areas such as the sky.

Then view the image at 50% to get a more realistic feel for what the end product will look like after printing. If you discover chromatic aberration (color bleeding) in the image, you can remedy this with a raw converter. (When you need a large image file with as much information as possible, you should take photographs in raw formats and then develop the image digitally in a raw converter. If you are taking photographs for a website, just use the JPEG format. However, if you are taking spontaneous shots using JPEG, it would be a pity if you then wanted to make large-scale printouts of the images.)

In order for your image to look as fresh as possible, place a white image against a white background. This way you will be able to see how white it is and can adjust it accordingly. Same with black, place a black image against a black background and you'll see just how black it is. There are so many nuances of white and black that an image with white in it can so easily look a bit grey, and hence dirty.

//Maria Stranger
What can you use a 100 MB image file for?
We have collated this and lots of other useful information in our Quick Guide, which you can download by clicking on the arrow. Perfect for printing out and having on your desk when you need quick factual references on image usage.

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Quick Guide»
Tips - affordable for web usage!
Three friends.
Images for web usage at USD 32
Quality images don't have to be expensive! Visit our website and discover our new price list, which includes affordable alternatives for digital media publishing.
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MEETING
It's at meetings that everything has its beginning. We asked our Account Managers to interpret the word "meeting" with images. See their entire hand-picked selection by clicking on any of the images below.
Girl and dog.
Shadow on building.
Girl looking at an elephant.