Prepare photos for printing in Photoshop with Luminosity masks

To print your pictures two posibilities exist: Printing at home or taking your photos to an professional print shop. Printers which offer a decent quality are very expensive. That's why I usually assign a print shops. A review about one online print shop where I placed an order recently will follow soon. This article is about the adjustment which I enable before I send a picture to an online print shop.

There is always one fact to consider independently from the material you want to print on. Pictures at a computer screen look brighter than a print on paper or canvas. That's because a print has no back lightning contrary to a computer screen. The result are prints which are too dark. You will notice this first at parts of the picture which are dark anyway. That's why I brighten the shadows of my pictures before printing. It is important to limit the lightening to the dark parts of the pictures. Otherwise light parts could become much to light. The best way to manage that is using luminosity masks in Photoshop. These are layer masks whose transparency depend on the brightness of the photo. Due to that fact your adjustments only effect lighter or only darker parts. Creating luminosity masks requires a lot of different tasks why I recommend to download a Photoshop action. I downloaded the action on the site of Jimmy McIntyre. You just have to subscribe to his weekly newsletter which is factful and worthwhile to read!

The first step if I adjust a picture for printing is deleting all the luminosity masks I used for developing the picture before. Why? When I developed a raw file in Photoshop I create the luminosity masks first. Afterwards I accomplish the adjustments of color, brightness and contrast. One of my last steps is distorting and skewing the picture to revise perspective-based distortion. At the end I remove sensor dust with the clone tool. Because of these two last tasks the created luminosity masks aren't coincident to the picture any more. Using this masks wouldn't affect the parts of your image whose brightness you want to adjust.

After deleting the masks I create new ones with the action of Jimmy. The next picture shows a spiral staircase which I photographed in Cologne. At the right side you can see the luminosity masks I've created.

18 masks in total does exist. Six each for the bright, medium bright and dark parts of the picture. The best masks for lighten the dark parts is brights 1 or brights 2 after you inverted it. But let's do first things first: Choose the channels panel next to the layers panel and leftclick at brights 2 with holing the STRG-key. A new brightness-based selection is created. That's how the mask looks like:

White parts are 100% transparent, black ones not at all. The different shades of grey show transparency values in between.

Go back to the layers panel and create a curve (Gradationskurven in the German Photosho version) adjustment layer. Your mask will be used automatically for this adjustment layer.

While your layer mask is still activated press STRG+I. The mask will be inverted. Now change the curve a little bit, like the following picture shows:

The result should still look good. If you have the feeling the picture is just a little bit too bright for viewing at your screen you did a perfect job. If the picture is much too bright you should adjust your curve. Here is my before and after: