Photoshop CS3: Resizing An Image With and Without Resampling

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When it comes to resizing an image using photoshop CS3 you have two options.

Resizing with resampling
Resizing without resampling.

This article will show you how to do both.

Resizing With Resampling
If you intend to make an image larger using resampling you will need to use what is known as interpolation. Interpolation is used when photoshop needs to add information – in this case new pixels – that weren’t already there. You will need to choose an interpolation option from the pop-up that will appear in the image size dialog box. There are a number of options to choose from.

Bicubic will give you the best result but this takes the longest amount of time. Nearest neighbour is the quickest option but this is also the least accurate. Bilinear will give you a medium quality result. Bicubic smoother is for enlarging images and this will give you a smoother finish. Bicubic sharper is for reducing images and is especially useful for web images.

If you are resampling up you will be adding pixels to your image and your file size will increase.

Choose Image > Image size. In order to keep the overall dimensions of your image but increase the resolution make sure that you have the resample image box selected. Select the constrain properties that you require and then enter a higher value into your resolution box. Your file size and total number of pixels will have increased your width and height setting will remain the same.

You should try as best as possible to avoid resampling up as you will be adding pixels without increasing the quality or the detail of your image. If you are scanning an image try to scan it at the size you intend to use.

When you resample an image you may find that you have some blurring. You can use the smart sharpen or the unsharp mask filters to help to compensate for this.

You can also sample down images which means discarding of some of your unused pixels. The result in this case will be a smaller file size. To resample down again choose Image > Image size. If you wish to keep the overall dimensions but decrease the resolution of your image you will need to make sure that the resample box is selected. You should also leave the constrain properties box selected as this will maintain the images proportions. Next reduce the value in your resolution box.

Your file size will go down and the amount of pixels contained in the image will also decrease. Your width and height will remain the same.

To reduce the dimensions of your image but keep the resolution the same follow the same process but this time change the values of your width and height. You will have a smaller image but your file size and resolution will be the same.

Resizing Without Resampling
Resizing without resampling is essentially making your image bigger or smaller without changing the total number of pixels contained in the image. What happens is that the dimensions of the image change but the file size stays the same. The resolution of the image also changes.

In order to decrease the size of your image without resampling you will need to choose Image > Image size. You will need to make sure that the resample image checkbox is deselected. Next enter a lower or higher value in the width and height boxes or change the resolution. If you change either the other measurements will automatically adjust. Remember that your file size will remain the same and no additional pixels will be added to your image. If you make your image smaller the same number of pixels will be packed into the smaller area.

It is important to note, that when you make an image smaller without resampling, the pixels will get smaller and this will effectively increase the resolution of your image. If you make your image bigger the pixels get bigger and this can lead to a jagged or blocky effect as you are reducing the resolution of your image.

So there you have it, how to resize an image using photoshop CS3.

Tags: photoshop, Photoshop Tutorial, Resampling an image, Resizing An Image

2 Comments to Photoshop CS3: Resizing An Image With and Without Resampling

1. 

   This is definitely an area I’ve overlooked in the past…
Jena Ardell on November 7th, 2008
2. 

   this is really nice to know how to make the image bigger with the best results. Thanks
Nick Nieto on November 7th, 2008