If you are completely new to photo editing and are not yet familiar with post-processing software functions, it might seem complicated to achieve simple tasks, such as cropping, resizing or rotation an image. This basic tutorial is aimed at people who are entirely new to Photoshop, since these functions are essential elements of editing and serve as pillars for more advanced practices. However, Photoshop is a very advanced software and it is priced accordingly, so if you are just interested in performing these basic tasks and don’t plan to learn any advanced editing techniques in the future, purchasing Photoshop might be a waste of money. These basic functions are available on much cheaper programs such as Photoshop elements, or you can even perform them online for free with programs such as Pixlr. While I discuss all the steps for these functions on Photoshop CS6, these steps and concepts are similar on all the other programs.
When I am taking pictures I am usually focused on many important compositional elements which are difficult to correct in post-processing and I will often miss simple irregularities, such as tilted horizon. But it is not a big deal because horizon level can be easily corrected in post-processing. I also try to compose my images with enough additional space on the sides, in case I might want to crop or slightly rotate my image. In this case, knowing how to perform these editing functions in post processing really helps. Also, having a camera capable of producing large resolution is a big plus, especially if you are planning to do large prints. So without further ado, here are the steps to crop and resize your images.
There are many reasons you might want to resize a photo, whether you want to post a small image online or print a reduced photo you will have to use resize image function. To resize an image you can go to Image>Image Size on the top Navigation Panel or just press [Alt]+[Ctrl]+[I] (Mac users press [Cmd] instead of [Ctrl]). This will bring up an Image Size window. Here you can either change a Pixel Dimensions or Document Size and the program will automatically calculate all the other proportions. You can also set the dimension to be presented in percentages relative to the original size rather than pixels. Remember, that the Resolution should be 72 pixels per inch if the photo is intended to be viewed on a screen and preferably at least 300 pixels per inch if it is intended for print. I also recommend checking Scale Style and Constrain Proportions boxes to be sure that all correct image ratios are maintained. Additionally, in my opinion the best results are achieved when Bicubic option is selected through Resample Image selection.
Resampling is a technical term for changing image size. There are several kinds of resampling. Upsampling is a term used for a process in which an image is increased in size beyond its original dimension. This will always decrease image quality. Downsampling is conversely a process by which an image is reduced in size, which typically maintains image quality. However, there are several things to consider. If the Resolution of the original image is 72 pixels per inch (ppi) and you need to print the photo, then you are better off increasing resolution to 300ppi. Increasing Resolution will increase Pixel Dimension but will not affect the actual document size. In this case Photoshop will automatically try to guess and predict pixels in the additional space created by increased dimension. While Photoshop is not the best program to perform such guesswork it is surprisingly one of the cheapest. On the other hand, just increasing Pixel Dimension on images intended for screen viewing will increase image size but noticeably decrease image quality. Therefore, there are two useful reasons to resample a photo. When you have an image with a large Pixel Dimension but small resolution, you can increase resolution for print but decrease Document Size to match your print size. Or, if you have a large resolution, but the image is intended to be viewed on screen you can lower the resolution but maintain the same Pixel Dimension. In both cases the image quality will be preserved.
Change Canvas Size
Another function you might encounter when dealing with sizes is Canvas Size. To understand how this function operates imagine that you look at your image through a frame. Originally this frame is the same size as your photo but you can change the size of it. If you increase this frame then you will see a background on which your image is placed but if you decrease the size of this frame you will see less of your photo. You can change Canvas Size by various points such as pixels or percentages. You can also choose an anchor point with which you can select from which direction the image will be cut or increased. Additionally, if you are increasing the canvas beyond the size of original image you can choose what color will fill the void.
Image Rotation and Cropping
If you don’t want to keep an entire image, but only want to select and save a section, you will need to crop. There are a couple of ways you can achieve it. The most logical way is to use a Crop Tool. Select it from a toolbox and drag through an area you wish to crop to. You can hold [Shift] to force the selection into 1×1 ratio or hold [Alt] to have the selection center around your initial contact point. Notice Width and Height boxes on the top Options Bar. If you use them they will define a specific ratio. For example: if you are cropping to prepare an image for a 4×6 print you can set those boxes to 2×3 or 4×6 ratios.
Once you finish your selection you will see areas that are outside of your boundaries become shaded. This illustrates what will be eliminated once the crop is complete. Check top Options bar, notice Cropped Area section. Delete and Hide choices are responsible for what will happen to eliminated area once crop is performed. If you select Delete, obviously those areas will be gone, but if you select Hide they will not be visible because of the Canvas Size but can still be accessed by moving the layer around.
Additionally, you can select how a crop box is presented. It can be blank, have Rule of Thirds markings or have a grid placed over it. This can help you achieve a better composition. You can also rotate a crop box by placing a cursor on one of its four corners. And finally, you can play around with appearance of shading of extra areas or remove it completely.
Once all changes are complete and you are satisfied, hit [Enter] or a checkmark on the top Options Bar to finalize crop.
Another way to achieve crop is to use Marque Tool. Simply drag over an area you wish to crop and go to Image>Crop on the top Navigation Panel. You can hold [Shift] to define 1 to 1 ratio or [Alt] to have the selection center around a starting point.
Additionally you have several useful options when using Marque Tool for selection. Refer to Style section of the top Options bar. Here you can choose Normal, which is free hand selection; Fixed ratio, where you can set ratios, just like with Crop Tool; Or select a fixed size, if you want your selection to be very specific.
Occasionally you have a tilted wall or horizon on your image, that’s perfectly fine and it happens to everybody. There are two ways to correct it. One way is to manually rotate a layer, while another way automatically calculates rotation.
To help you manually rotate a layer you will need to have Rulers activated. If they are not, go to View>Rulers on the top Navigation Panel, or press [Ctrl]+R ([Cmd]+[R] on Mac). To set a perfectly straight line move your cursor over the ruler (which is located on top or left side), press left mouse button and drag the line on your image. This will create a perfectly straight line. If you dragged from the top the line will be horizontal. Next, duplicate a layer you need to rotate. Remember that initial background layer is locked and cannot be rotated this way. Then go to Edit>Free Transform or click [Ctrl]+[T]. You should see tiny boxes appear around the edges of that layer. Move your cursor a bit beyond any corner box until cursor icon turns into a rounded arrow and turn the layer in any direction. When you are in Free Transform mode you can also manually specify angle and skew on the top Options Bar. Once satisfied, click a checkmark on the top Option Bar or hit [Enter].
To use Photoshop’s automatic angle calculation function you will need to use a Ruler Tool. Select a Ruler Tool from the Toolbox and drag it along the line you would like to be leveled. This would usually be a horizon or other indication of flatness. Your Ruler line doesn’t have to cover the entire area of the image; it just needs to be long enough to have an angle, which is basically longer than a dot. When done go to Image>Image Rotation>Arbitrary. A window will pop up with a suggested angle. Hit OK to complete. Remember, this action affects the entire file. It will rotate all the layers and increase canvas size. If this is not acceptable for you, then consider using the first method.