If you are altering your images before printing, it’s important to know what impact your changes will have. The most common image adjustments are cropping, choosing a very specific part of an image to print and discarding the rest, resizing and colour changes or manipulation.
All of these actions will have an effect on how your image will print. It’s important to understand why to make sure that you do not get unexpected results.
Probably the most common programs to alter images are Adobe Photoshop and Lightroom but you will see almost identical options in other image editing software. Here we will look at the settings under the ‘image size’ menu option (screenshot below may look different depending on which program you are using). Your image properties will change if you crop your image, also it is here that you control any resizing.
This window shows how many pixels wide and high your image is and how large you will be able to print at a given resolution or pixels per inch (ppi). Underneath this are three important tick boxes which come into play if you resize your image in any way.
Scale styles, if ticked, will ensure that if you have added any other layers or effects to your image, everything will resize at the same rate.
Constrain Proportions, when ticked, ensures that when resizing your image it isn’t stretched in any way and stays perfectly in proportion. If you change the height of your image then the width will automatically be set. Only un-tick this option if you want to intentionally stretch your image in either direction.
Resampling is VERY important when resizing despite being the last option.
If you were to try and alter the document size of your image with resampling NOT ticked, you would not have the ability to change the pixel dimensions and the resolution will change. If you typed in a larger size, Photoshop would lower the resolution figure to let you know that as you increase the size at which you want to print, the resolution or image quality will drop. Similarly, if you reduced the document size the resolution would increase.
When resampling is ticked, the pixel dimensions can be altered because Photoshop will perform clever analysis of your image and add pixels when you enlarge your image, or remove pixels when you reduce it in size. This now means that you can make your image much larger, and apparently print the image at exactly the same resolution it was at its original size. For everyday photos this will be ok however if you are printing high end shots for resale or for display at a gallery or exhibition we recommend NOT ticking resampling if your want your work to be the best it can be. We also recommend not ticking this option if you want to make any major size adjustments. Your image will not be nearly as sharp as it was originally. Whether enlarging or reducing, using resampling will degrade your image quality.
Underneath all of these options is another drop down menu. This controls the way pixels are added or removed when resampling. The options are pretty self-explanatory and show recommendations for each option.
Colour, calibration and profiling
This subject can almost get as technical as you like and we could talk for days, potentially weeks about the science behind colour and all the factors involved. It can also be a very subjective topic with individuals having their own preferences based on style and experience. We will try and keep it as short and sweet as possible.
Unless the monitor or screen you are using to view and edit your shots with is calibrated, it will be almost impossible to guarantee that your prints will match what you viewed on screen full stop. It would be like Russian roulette.
The type of monitor or screen you are using will also affect how images are interpreted. On lower end LCD screens, colours will appear different depending on the angle at which you are looking at the screen. Traditional CRT monitors, although no longer manufactured, were not prone to this problem. If you are looking to go pro then spending a little bit more on a higher quality LCD screen should solve this problem but always do your research before parting with your hard earned cash. LCD screens are often set to a very high brightness to give that wow factor. It would be very difficult to ever achieve this brightness on paper and so we strongly recommend calibrating your screen properly.
External screen calibration software such as LaCie, Spyder or X-Rite to name a few, will help your screen to display the most accurate representation of the actual colour values within your images. They can also take into account the lighting in the environment you are working in. You may find your display a lot more muted after a calibration. This is the difference between viewing your images on a screen which emits light, and viewing them as ink on paper which actually absorbs light.
The two main colour spaces used in photography, sRGB and Adobe RGB 1998. You can usually switch between colour spaces in your camera settings although some may default to one or the other. In brief, sRGB is the older of the two colour spaces and so is more widely used on display devices in everyday life and is predominantly used when saving images for use on the web. Web browsers are catching up however and most now handle Adobe RGB just as well. If you are printing you will achieve more vibrant results using Adobe RGB as it has a wider colour range. This colour space information is embedded into the image for translation by the printers.
If you are serious about your photography and have bought a camera with technical ability that matches your ambition, the alternative is to take all your shots in RAW format which has no colour profile information and has an even wide colour range. Most professionals will use this format as it gives them more colour detail to play with when editing their shots in preparation for print. After editing you can save you image using either sRGB or Adobe RGB as your chosen colour space.
You can find plenty of information by going to the help menu in Photoshop itself, online on Adobe’s help pages of course plus there are many photographic websites and forums where these issues are covered and often debated in lots of detail.