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Resizing aka Resampling an Image
How to resize/resample an image using Photoshop's Image Size function.
Resizing / Resampling
When you are using images for screen presentation, i.e.: web pages or PowerPoint presentations, your images should be 72 ppi to insure that they will display at the proper size in all browsers and applications.
To preserve the image resolution (72 ppi) but make the image appear smaller on the screen, you must resample the image which will change the actual Pixel Dimensions of your file.
When you increase the number of pixels in this section of the dialog box (upsampling), Photoshop adds pixel data to the image, and when you decrease the number of pixels (downsampling), Photoshop removes pixel data. Whenever data is removed from or added to the image, the image quality degrades to some extent. Removal of data from an image is usually preferable to the addition of data, because upsamping requires that Photoshop guess which pixels to add. This is a more complex procedure than guessing which pixels to remove, which is what Photoshop does when you downsample.
[The above is paraphrased from the Adobe Knowledge Base website. For a more precise explanation, see: http://www.adobe.com/support/techdocs/331327.html]
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Basic Image Editing Techniques in Photoshop
Adjusting Levels (Light / Dark)
- Comparing Our Results
- Resizing/Resampling
