How To Resize Images And Maintain Original Sharpness

You have a nice big beautiful photo. It is gorgeous. But you need it much, much smaller, and by the time the file is down to the right size, you might find that the image has started to take on a blurry look. This is a real problem with resizing images, but luckily in Photoshop there's a very simple solution.

This tip will only work with Photoshop CS and CS2. If you don't have a CS version yet I recommend you try and get one as soon as you can, because they are full of powerful new features. For earlier versions of Photoshop there's a workaround at the end of this tip.

When you want to reduce an image go to the Image> Image Size menu. Click on Resample Image and choose Bicubic Sharper from the drop-down menu. This is the best setting for making sure that an image doesn't blur. The example photo of the flower started at 2,000 pixels across. I stepped it down to 250, and then again to 125 with almost no loss of sharpness. For enlarging an image select Bicubic Smoother.

I found this to be such an effective trick that I wished it had been the default setting in Photoshop for the Image Size menu from the start. Then I discovered I could set it as the default myself. All you need to do is go to Preferences> General and you'll see Image Interpolation and there you can pick Bicubic Sharper from the choices.

Another thing to keep in mind when resizing is to try to do it only once on an image. Many people will resize repeatedly as they search for the perfect fit for a design element, and then end up with an image with a lot of blur. It's always better to experiment on a duplicate of the image. Then, when you've settled on the final dimensions, you can go back to the original and resize it just once.

Pre-CS Workaround
In earlier versions of Photoshop simply zoom out so that your window and image are at either 50% or 25%, and then take a screenshot of the image window at this new reduced size. You'll find that the image will maintain its sharpness. Now open the screenshot in Photoshop, and crop and save. The trick to making this work is to use either a 50%, 25%, or 12.5% view size before making the capture. If you view the image at 66.7%, 33.3%, or 16.7%, the image will not be as sharp due to the way Photoshop draws images at those sizes.

Troubleshooting
Never resize a GIF image. First change the mode to RGB Color (Image> Mode> RGB Color), and then resize. You can still save your resized image as a GIF, just do not apply resizing while the image is in the GIF mode.

Alpha Channels: An Introduction

If you have ever found your self selecting and then re-selecting the same portion of an image in Photoshop then you are in dire need of Alpha Masks.

Scenario: Imagine that you are working on a Photoshop project where you had to carefully select something. You took about 10 minutes to successfully select something. Then you worked in the selection for another 10 minutes and then you deselected only to realize that you forgot to apply a stroke (Edit > Stroke) to the image. What now? You’ll have to spend another 10 minutes re-selecting.

The whole re-selecting process could have been avoided if you had used Alpha Channels to save your selection.

Selecting an Alien Flower

1) Here I have selected what appears to be an alien flower. It took me about five minutes (I selected in Quick Mask mode). I wouldn’t want to spend another 5 minutes re-selecting it in the future.

Saving the Selection For Ever

2) So now I want to save this selection. With a stroke of genius, I glide my mouse pointer with extraordinary skill all the way to the Select menu. While in this menu I click on Save Selection. Tada! I have successfully saved the selection. I’ll never have to re-select that alien flower ever again.

If you did the same then you should see something like the following window appear:

Enter a name and click ok.

Wait? What Happened?

3) Nothing appeared to happen but if you go to your Channels Palette ( Window > Channels ) then you will see an Alpha Channel. This is the saved selection.

Moment of Truth.

4) De-select the current selection ( Press CTRL/CMD+D). Now if you want the selection to come back then just CTRL/CMD+ Click on the new Alpha Channel (called Alien Flower in this example) and your selection will return. Whew!

Not only will this selection re-use allow you to save time but now you have access to a whole new list of channel features.

Some Facts

5) If you click on the Alpha Channel, the entire image will turn black and white.

• The areas that are not selected will be black
• The areas that were with in the selection will be white.
• The areas that are translucent or partially transparent will appear as shades of gray.

This view is helpful because you can check if you have errors in your selection. If your selection is fuzzy then you can adjust the levels ( Image > Adjustments > Levels ) or sharpen the selection ( Filter > Sharpen > Smart Sharpen ).

You are allowed to use most of the filters and image adjustment tools in this view. You can use this for your advantage and create lots of fun and useful effects. I’ll try to cover some of these in the days ahead.

You can also use the paint brush, paint bucket, or pencil tool to reshape the selection. If you paint black then that area will get deselected. If you paint white then those areas will get selected. Gray areas will be semi-transparent.