Preparing Images For Print

Transcription

1 Preparing Images For Print The aim of this tutorial is to offer various methods in preparing your photographs for printing. Sometimes the processing a printer does is not as good as Adobe Photoshop, so it s best to get things right before you print to prevent any major changes. Task Copy one of your favorite photographs and convert it to CMYK mode and 300 DPI. Set its size in inches to what you want it to be when printed and make any colour changes. See the differences between the two images. Nick Kind course@nickkind.com

2 Introduction The best part about photography is actually printing out your pictures and showing them off. However, this can be the most frustrating part! The output from a printer can be totally different to what you have on your computer screen. Factors such as image resolution and colour modes need to be considered, but there are so many other variables such as screen colour settings, screen brightness & contrast, printer ink levels, printer condition, type of printer. In fact, it s very hard to get the process 100% accurate. If you get as many parts of the process right then your results are going to be better. Taking more and more work away form your printer and handling it in Photoshop is the right way forward and the more practise you do, the more you will fine tune your print process. But also getting to know your equipment is important. This lesson will introduce you to some techniques that will help your print process achieve good results.

3 300 DPI Print Quality The first thing to consider is your resolution. Most digital cameras create an image that has a resolution of 72 DPI or 180 DPI. DPI = Dots per inch. It is the amount of actual dots that make up your picture. Industry standard print quality is 300 DPI. Lets have a look at the comparison. 72 DPI 300 DPI Imagine both of these boxes are a square inch in size. The box on the left has only 72 dots in it to make up its picture and the box on the right has 300, obviously this one is going to have a much sharper feel to it as there are more dots. (The dots in the diagram are not to scale). If we sent a 72 DPI image to the printer and specified a size, for example A4, it will resize the picture and fill in the gaps itself. This will reduce the quality. For the same reasons we do not take a photograph on our digital cameras in Black and White mode because our processing on Adobe Photoshop is much more powerful than the camera, we do not let our printer resize our image. So if we want to get a good quality print, the first start is to convert our photographs to 300 DPI.

4 300 DPI Print Quality To change your image to 300 DPI in Adobe Photoshop Elements 2, select Image from the program menu bar, then Resize and select Image Size. This brings up the Image Size window that we are already familiar with. Simply input the value of 300 where it says Resolution and make sure pixels/inch tab is selected. You will notice that the pixel values have changed when you input 300. This is because it is going to resize the image and make it larger. Press OK and see what happens to your image. The image is now a lot larger on your screen and when you save it its file size will increase too. But in terms of printing it is still the same size - note on the windows above the document sizes did not change from 10 x 8 inches. Why is the image now larger on the screen?

5 300 DPI Print Quality The image is larger on your screen because it is now displaying a 300 DPI image on a 72 DPI screen. The dots have increased per inch, but the actual image size has not changed. If you imagine that square box again, but lets look at them slightly differently. The box on the left is 1 inch square at 72 DPI and the box on the right is 1 inch square at 300 DPI. You can check this by looking at the rulers on the windows of each boxes outlined in red, they both say 0-1 inch. Because there are more dots in the 300 DPI box it has to be displayed larger on the screen as the screen can only show 72 dots per inch. If both of these images were to be printed out they would appear exactly the same size, only one would be better quality - can you guess which one? Try for yourself and make up two new images in the same way. Click File and select New. This brings up a window to create a new canvas. Make one 1 inch by 1 inch and 300 DPI and another new canvas the same at 72 DPI, you will see something similar as the above screen shot with two boxes at different sizes. Note - it is important to put your pictures into 300 DPI mode before working on them in Post Production as the process could result in loss of quality of the tools applied.

6 Print Size Now we know how to make our photographs at 300 DPI. But what if the printer still resized them, and why would it do this? Another thing to consider is your Print Size. This requires a little more thought into your final result. But if you want your picture to be 10x8 inches, then why not physically make it this size in Photoshop rather than selecting a particular size on the printer menu. This part is easy. As before click File from the program menu bar and select New. This New canvas window appears. Input 10 inches for the width and 8 inches for the height. Remember to set the DPI to 300. Press OK when you have finished. You have now created a New Canvas in Photoshop. It should look something like this.

7 Now lets open a photograph and put it into this new canvas. You can see there are two images now loaded each with one layer a piece. Now we want to put the photograph into the blank canvas. We do this by using the same technique in Post Production 02 for Dragging a layer. Click the left mouse button and hold it down on the layer called Background in the layers window (it should have a thumbnail image of a tree on it). When the layer turns red move the mouse over the new window we created that is behind the photograph. If the photograph window completely covers it, move it to one side. Now let go of the mouse button. The photo should be inside the new window. Print Size Your screen should look something like this. Close the other photograph window as we don t need that anymore. Notice that the photograph is quite small on this new canvas. That s because we have put a 72 DPI picture onto a 300 DPI picture.

8 Resizing the Photograph to fit the Canvas Now we need to fit the photograph to the new window size of 10 x 8 inches. We can do this by using the Move Tool. When you select the Move Tool form the Tool Bar you will notice a border appears around the photograph with small boxes at each corner and on the sides. These are marked in red below. If you move the mouse pointer to the bottom right corner of the photograph you will see it change to the double ended arrow symbol. Now if you click the left mouse button and hold it down you can move the mouse around and see that the photograph size is changing. Get a feel for how it moves. Simply pull the photograph edges to the edges of the canvas, it should snap in when you get close. You can let go of the mouse button and move to the top left hand corner of the image and the same thing will happen. Simply click and drag to move the remainder of the image. Completely cover the white behind and fill the canvas with the photograph. Press the ENTER key when you are satisfied with the new size of the photograph.

9 You should now have something like this. The picture of the tree has completely covered the white background and fills the canvas window. This image is now ready for printing out. When you select print, make sure you set the print size to 100%. This will not resize you photograph at all and print out at exactly 10x8 inches. We are also ready to carry out any Post Production if you wish to do so. Resizing the Photograph to fit the Canvas After Post Production.

10 Save as PSD (Photoshop File) If you wish to come back to this picture later and don t want to loose any of the layers. Then saving it as a PSD rather than a JPG will store all of this. A PSD is a proper Photoshop Document and is what we call a Source File. Similar to Microsoft Word calling its files DOC, or Microsoft Excel XLS. Photoshop files are much larger in file size than JPG s because not only do they store all the layer information, but they are not compressed. To save as a PSD simply click File and then select Save As. This file has been called Life.psd and will be saved to the Desktop. Usually when there are more than one layers in a Photoshop file it will default to the PSD setting shown in the format box. If not, then select the Photoshop (*.PSD, *.PDD) from the drop down list, it will be at the top. Make sure the Layers box is ticked otherwise it will flatten the image to just one, similar to a JPG. This completes the saving as a PSD process. 10

11 When you print out a photograph the printer changes the colour mode to a new mode called CMYK. This stands for Cyan, Magenta, Yellow and Black (black is called the Key colour). Up until now everything we have used has been in RGB mode, Red, Green and Blue. This is the digital camera and the computer screen. Like TV, RGB are the colours used for light and are mixed together to make the rest of the colours. CMYK are the colours for print and are mixed together likewise. But when we print out, certain colours may look different. This is because the frequency and range of RGB colours is much further then the range in CMYK. An example of an RGB image and CMYK conversion is shown below. RGB Mode CMYK Mode The first thing to notice is we have lost that deeper blue and the gradient of colour has been lost around the edge. This is because the particular blue used around the tree can only exist in RGB mode and has been flattened out by the CMYK conversion. It has ruined the picture. How can we overcome this? One way would be to work in CMYK mode right from the begging so we never need to convert. This is very good practise, however many filters and tools do not work in CMYK mode, so sometimes we are forced to work in RGB. In these situations it is best to save your picture out as a JPG. Keeping the PSD file in RGB mode. If we were to convert the PSD with all the layers in it the process will degrade the colours more as it is not flattened. An example of this is shown on the next page. CMYK Mode 11

12 RGB Photoshop File (PSD) CMYK Converted Photoshop File (PSD) RGB Flattened JPG CMYK Converted Flattened JPG Both the RGB images on the left are identical, but the CMYK conversion on the right both show changes in colour. Can you see that there is more colour change on the PSD file than the JPG? One area to compare is the top left hand corners of each CMYK image. The JPG has kept the darker blue and the PSD has been flattened to a lighter blue. In order to get our colours correct again we work on the flattened JPG and convert it to CMYK. Now, with the original RGB image on the screen as well, we simply compare the two images and try to match them. There are many Tricks around to complete this and it does depend on the image you have, but tools such as Colour Variations, Hue & Saturation, Brightness & Contrast will all play their part. But for this particular image there is one simple trick we can use that we have already learned. Note - Adobe Photoshop Elements 2 does not have a CMYK mode in it. So for the rest of this tutorial we will use Adobe Photoshop CS2 (the professional version). Save your PSD as a JPG called Life RGB.jpg and save another as Life CMYK.jpg. Close the PSD file and open the two JPG s so they are side by side on the screen. Convert Life CMYK.jpg to CMYK mode by clicking Image then Mode and select CMYK. CMYK Mode 12

13 CMYK Mode Your screen should look something like this. Note the colour difference between the two images. The CMYK image is on the right and the RGB on the left. Duplicate the layer on the CMYK image and set its blending mode to Overlay. The colours are too saturated now, so slightly reduce the opacity of the new layer to around 65%. You will see the image looking very similar to the RGB one. 13

14 This is a very quick and easy method to get the photograph looking correct again. Sometimes you will never get it exactly right, but the closer you get it, the better the results and because you are working in CMYK mode, these colours are less likely to be destroyed by the printer. RGB Mode CMYK Mode CMYK Mode We can see there isn t much difference and the colours are close to what they were before the conversion. All we need to rely on now is the condition of the printer, the level, quality and temperature of the inks and the quality of the paper! 14