Tutorial

The Best Method of Image Reduction in Photoshop

By on November 22, 2016

We live in the era of high-resolution photography equipment where lower resolution is no longer a problem. Most DSLRs, from beginners to professional level, are able to shoot in 22MP or higher resolutions. Even smartphones have long surpassed the resolution barrier of film emulsions of the 35mm era.

That brings me to the purpose of this tutorial. Having such high MP sensors available to us, the need to enlarge an image after capturing it doesn’t exist most of the time unless you print your images on large canvases or for outdoor advertising etc. Most of us share their images online and we don’t even need 16MP for online sharing. So the question is “Why resize an image?”

The simple answer is “Reduction”. Instead of the need to enlarge an image for sharing, we now have to downsize our images. Scaling an image, be it enlargement or reduction should be done in the right way. Photoshop offers multiple ways of reducing an image size or pixel dimensions. Let’s take a look at the different options.


Interpolation Methods

In Photoshop, when you choose the Image Size option (under Image> Image Size), you are given the following options as shown in the snapshot below.

Photoshop Image Size dialog box

Photoshop Image Size dialog box

By default, the interpolation method used to resize images is set to “Automatic” as shown above. If you click on the drop-down menu, you will see that there are many other options available to use.

Photoshop Interpolation Methods

Photoshop Interpolation Methods

From the image above, we can see that Photoshop offers 7 different options or interpolation methods to resize images. Let’s go through each one of them.

Automatic: As the name suggests, this method does everything for you. In my opinion, it does much more than what I’d like it to do, especially when reducing image resolution. When reducing image size, the automatic method does two things:

  • Size reduction
  • Sharpening

My gripe with this method is the way it applies sharpening to an image after reducing the size. The amount of sharpening that Photoshop applies is excessive which results in unpleasant halos around edges and areas of high contrast. Therefore I strongly advise not to use this method when reducing image size in Photoshop.

Bicubic Sharper (reduction): Don’t be fooled by the word reduction in there. It does reduce the image size just as the name suggests… BUT it also applies sharpening which is excessive and ugly. Basically, this is THE method Photoshop picks if you choose the Automatic option when reducing the image size. Please don’t use this method.

Bicubic (smooth gradients): One of my preferable modes when reducing image size. This method only reduces the image dimensions without adding any kind of sharpening to the reduced image. Colors remain intact and details are well-preserved. It pretty much keeps the image the way the original is so when you apply sharpening, the result is a much higher quality image minus any artifacts such as halos.

Nearest Neighbor (hard edges): This method preserve edges in an image data which eliminates the need for any sharpening, as the image looks sharpened and crisp. The problem with this method is that it doesn’t work well for finer details. This method doesn’t blend color and texture information together smoothly and therefore the output looks edgy and sharp, which may work for line art and solid color graphics, and is definitely not ideal for continuous-tone images such as photographs.

Bilinear: By far the best option for reducing image size in Photoshop and my preferred method, Bilinear reduces the image while maintaining the aesthetics of the original. It works very much like Bicubic (smooth gradients) and you may not see the difference between the two. But on fine textural detail, I have found Bilinear to be performing better. And I highly recommend this method.

Once you reduce the image size, the next step is to apply sharpening. To learn more, check out my tutorial on “3 Steps for Smarter Sharpening in Photoshop“. There are two more interpolation methods that are, “Preserve Details (enlargement)” and “Bicubic Smoother (enlargement)”. I have not covered those two because they are not applicable to image reduction but rather image enlargement.

That’s all for now. Give it a shot and notice the difference between the different interpolation methods. As always, feel free to ask away in the comment section below. If you wish to receive these tutorials in your inbox, signup to my newsletter.

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HAMMAD IQBAL
DOHA, QATAR

Hi, I am Hammad Iqbal, a professional photographer based in Doha. Welcome to the "HI Blog" where I share tutorials, tips and techniques about shooting and post-processing images using Lightroom and Photoshop. Follow my updates by subscribing to my newsletter and discover with me the art of photography and post-processing!

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