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As almost every photographer will tell you, the knowledge of how to properly resize images is essential if one wants to maintain the quality of the final product. Luckily, the constant increase in the megapixel size of cameras means that it is easier for us to print the images we take on a larger scale without degrading their quality. It also means that it is much easier to crop images while keeping them sharp.
However, even with more megapixels, sometimes you may have to resize an image for printing or publishing to the web. This is especially true for photographers who wish to exhibit their photography in a gallery or upload it to their online portfolios.
If you are looking for ways to resize your pictures without losing their quality and sharpness, you can use Adobe’s Photoshop to do so. In this tutorial, we are demonstrating the process of resizing images by using Photoshop CS5.
It is important to understand the various functions that you can use to resize your images with Photoshop. The resizing process is usually done through the Image Size dialog within Photoshop. To launch this dialog, click on Image - Image Size in the top menu bar. You will then see a window like this:
Here, you can see various options to resize your imported picture. The one I am using is one from a trip to the beautiful valley of Swat in Pakistan. It was taken with the Sony SLT a-58, which is a 20.1 megapixel camera. Let’s take a look at the information this dialog box provides.
This shows the size of the imported file. In this case, you can see that it is 56.7M at the moment. Later, when we resize the image to enlarge it, you will notice how the size increases accordingly. The Pixel Dimensions increase as you increase the quality of the photo you have taken. This particular image has been exported as a JPEG file at the highest settings from a RAW file. If it were a JPEG file straight from the camera, the picture may have been smaller. Similarly, if this were a RAW file, the picture would have been much larger.
Underneath this information, you can also see the dimensions in Pixels as the unit. I find that this option is more useful for people who are looking to resize images to be posted on the web. For example, if you know that a certain website allows you to post images of only 600x800 pixels, you can control that from here.
Here you can see the physical size of the picture you are viewing. In this example, the image can be printed as large as 18”x12” without degradation of quality. You can view this information in other units, such as cm, mm, and points, as well by clicking on the drop-down menu.
You can also view the resolution of the image in ‘ppi’ (pixels per inch) here. Increasing or decreasing this number leads to a change in the pixel quality of the image.
Now that we have gone over the basics of how the tool used to resize pictures in Photoshop works, let’s see the different ways we can resize a picture without giving up too much of the quality.
Before making any changes to the imported image, we stress that you make a Duplicate Layer of it first. This can be done by right-clicking on the image layer and selecting Duplicate Layer. Duplicating the layer allows you to easily go back to the original image if something goes wrong with the duplicate.
In order to enlarge an image for printing, what you need to do is open the Image Size dialog in Photoshop and manually enter the desired Width and Height under the Document Size header. For example, I wanted to print the imported image at least 30 inches wide, so I simply changed the number to 30 inches in the width value field.
Note that if the Constrain Proportions box is checked underneath these settings, Photoshop will automatically adjust the height of the image in order to maintain the original aspect ratio of the image. If, however, you wish to have a very specific size, you can uncheck this box and change the height of the image manually too.
It is important to know that when you are enlarging an image, each pixel is essentially being divided into multiple ones. This leads to a drop in the quality of the image. To minimize the drop in quality, you need to choose the right type of resampling in Photoshop’s Resample Image option. For enlarging images, the best option is Bicubic Smoother which smoothens the transition between each pixel and causes the resulting image to stay fairly clear.
If you are unsure of how much larger you want the resultant file to be, then you can also resize it using percentage as a unit of resizing in Photoshop. To do this, simply choose Percent as the unit instead of pixels under the Pixel Dimensions header, and increase the number in increments of 10. This will increase the size of the image by 10 percent, and you can continue doing this until you are satisfied with the resultant size and quality.
In order to resize the picture into a smaller one using Photoshop, the best way is by cropping it. Using the Crop Tool in Photoshop is very easy. Simply click on the Crop Tool and you will see a small toolbar appear underneath the menu bar. Here you can input your desired width and height for the resultant image, or choose one of the preset dimensions from the drop-down menu.
After you have typed in the desired dimensions (in this case I have chosen 12inx12in for demonstration) simply click on the image and drag the mouse across the screen. A box will appear based on the dimensions you have chosen in the previous step. Once the box is made, you will be able to see which part of the image will be cropped out. If you are happy with the cropped image (highlighted inside the crop box), press the Enter key and you’re done.
In order to email an image or to post in on the web, it is important to reduce its size. To do this, go to File - Save for Web and Devices. A new window will open with options to resize the image for the web. On the bottom left of this window, you will see the current size of the image and the time it will take to be downloaded. At the right, you will see various options regarding the quality and footprint of the image. In order to make your image smaller, you can reduce the export quality of the file from the top right corner, or reduce the pixels of the image from the bottom right. You can change these options as much or as little as you need to for achieving the desired result.
So there you have it. These are the easiest ways that allow you to resize your images with Photoshop. Note that whenever you are expanding an image past its actual dimensions, there is bound to be a loss in quality because each individual pixel is being affected by this action. But whether you need to resize pictures for publishing online or to be printed and framed, following the steps in this tutorial will go a long way in ensuring that you don’t lose too much quality in doing so.