|
Get Photoshop...Resizing Vs. Resampling |
By:
David Peters |
|
|
Get Photoshop...Resizing vs. Resampling
David Peters
Contrary to what you may think, there is a difference between photo resizing and resampling although both are tools used to change the size of an image in Photoshop. Many people might believe the two terms are basically interchangeable; however how the result is accomplished is different in how it changes the building blocks of the image itself. Although this may sound drastic, the difference between to the two is all in one simple click. At the bottom of the Image Size dialog box, there is a checkpoint option that creates either the resizing or resampling of the image.
Under the Image Menu at the top of the screen, will be what is called the Image Size dialog box. This again is the one option determining resizing or resampling. An image is actually composed of tiny dots of color together called pixels. How the number of pixels is changed or not changed defines resizing versus resampling the image. Photoshop terminology refers to this as altering the pixel dimensions. Keeping the pixels number the same and only changing the size you wish the picture to print is called resizing. Photoshop refers to this is changing the document size of the image. But, if you in fact change the amount of pixels making up the image, it is known as resampling.
Image Resizing: Changing the size the image will print without changing the number of pixels in the image. Image Resampling: Changing the number of pixels in the image. Alright, now you know the definition of Image resizing and resampling. That's simple enough and don't worry because it really doesn't get much arder to do. You are only a step or two away from doing this with your own images
It is pretty simple once you know the difference, but how does it relate to your computer and how hard is this to really do? You can do this quickly and easily with your own photos in just a few simple steps
Photoshop's Image Size dialog box contains some key pieces of information and is separated into two main parts. Pixel Dimensions make up the top half, while the Document Size portion is underneath. Pixel Dimensions shows the width and height consisting of the number of pixels the image is made up of. It also displays the file size of the picture. The Document Size part also shows width and height, but these are the dimensions at which the image will print. The image resolution, also found in the Document Size section of the Image Size box is what these numbers are based from. So remember, he Pixel Dimension will change how an image is displayed on your computer screen or even on the web, whereas changing the Document Size dimensions will affect the print size of the image. Pixel Dimensions = web Document Size = print
We're not quite done yet with the Image Size box. It also contains three other pieces of information as shown below: Scale Styles - Deals with the affect of resizing or resampling the image on Layer Styles. Constrain Proportions - Enabled by default, it links the width and height of the image together. If you make a change to the width of the image, for example, Photoshop will automatically change the height, and vice versa, so that the proportions of the image remain the same and don't get distorted. Resample Image - THIS IS THE KEY HERE!!!
The Image Size box also contains a few more bits of information. You will find three more options below the Document Size section: Scale Styles - Deals with Layer Styles and how they're affected by resizing or resampling the image. Constrain Proportions - Enabled by default, links the width and height of the image together. If you make a change to the width of the image, for example, Photoshop will automatically change the height, and vice versa, so that the proportions of the image remain the same and will not distort. Resample Image - THIS IS WHAT YOU HAVE BEEN WAITING FOR!!!
We will touch a bit on Scale Style and Constrain Proportion, but it is that last box being checked or left blank that determines resizing vs. resampling. Remember that resizing keeps the pixel dimensions unchanged and only increases or decreases the size at which the image will print. Resampling however, actually changes the number of pixels in the image. The Resample Image option will be automatically checked by default. Basically, the dialog box still says 'Image Size' at the top, but its function now is as the Image Resample dialog box while being checkmarked. All options in both halves, the Pixel Dimensions and the Document Size, will be available to you.
With the Resample Image unchecked, the Pixel Dimensions sector of the dialog box will show how many pixels are in the image for the width and height, but you will no longer be able to change those numbers. They're visible for information only. The only option available is to change how large the image will print using the Document Size section. With Resample Image checked, the pixel dimensions are shown inside white input boxes which we can click inside of and type in new values, changing how many pixels are in our image.
You will notice other changes that happen depending on if the box is left checked or unchecked. The Scale Styles and Constrain Proportions options at the bottom of the Image Size dialog box are grayed out when 'Resample Image' is unchecked. Scale Styles is grayed out because it's only used when the number of pixels in an image is being changed. Since the number of pixels in the image remains the same with Resample Image left blank, the Scale Styles is not needed.
Image Interpolation Options When Resampling Images
Image Interpolation Options When Resampling Images
Time for the dictionary! "Bicubic" and "Bicubic Sharper" are what is called "iterpolation algorithms". Don't worry, simply put, this is what the Photoshop program does in regards to removed pixels when you resample the image to a smaller size, and how it handles added pixels when you resample the image to a larger size. Photoshop CS2 a third option called "Bicubic Smoother." Image quality can be compromised if you are unsure of which option to use when. Use these basic rules: Bicubic Sharper - Using this option when resampling your image smaller provides best image quality Bicubic Smoother - Using this option when resampling your image larger provides best image quality Bicubic - Typically not used as often being replaced with Bicubic Sharper and Bicubic Smoother
These options will be grayed out because they only will work for images that are being resampled. If all you are doing is changing how large or small the image will print on paper, you won't need these options.
Summary Image resizing - Keeps the number of pixels in your image the same and affects only how large the image will print (the Document Size). Image resampling - Physically changes the number of pixels in the image (the Pixel Dimensions). Resample Image - Option located at the bottom of the Image Size dialog box that controls if you are resizing or resampling the image. Checking the Resample Image, means you are resampling the image. Unchecked, you're simply resizing the image. Resample images by changing width and height values in the Pixel Dimensions section of the Image Size dialog box. It is used mostly when optimizing images for the web or computer screen. Resizing images by changing the width, height and/or resolution values in the Document Size section of the Image Size dialog box is used for printing the image.
About the Author:
|
|
Article Source: http://www.statssheet.com/articles/article77826.html |
|
|
|
|
|
