First things first, there IS a difference between photo resizing and resampling. Although they are both a Photoshop tool designed to change the size of an image, using the two terms interchangeably is not accurate. The method of resizing and resampling is actually performed differently. This difference is determined by how the image itself is changed. If this sounds complicated, it's really not. One small checkbox option defines the two. Opening the Image Size dialog box, you will see a checkpoint option at the bottom corner. This is the box you choose to resize or the resample 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.
Resizing vs. Resizing An Image
Resizing vs. Resizing An Image
Before we begin, it is important to understand what information is contained in the Image Size dialog box. Photoshop's Image Size dialog box is divided into two main sections. The Pixel Dimensions section is on top, while the ocument Size section is below it. The Pixel Dimensions portion displays the width and height of the image in pixels, and also tells us the file size of our picture. The Document Size section tells how the width and height at which the image is going to print. This is based on the image resolution, also found in the Document Size section of the Image Size box. An easy rule of thumb is that the Pixel Dimension section is what you would change for displaying an image on the web or your computer screen. The Document Size is what you would use to change the dimensions at which the image will print. Pixel Dimensions = web Document Size = print
Also in the Image Size box are 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 don't get distorted. Resample Image - THE IMPORTANT ONE!!!
We won't go into detail about the Scale Style and Constrain Proportion, because it is that last box that is the key to resizing vs. resampling. Keep in mind that resizing keeps the pixel dimensions the same and only changes the size at which the image will print, while resampling physically changes the number of pixels in the image. The Resample Image option will be checked by default. This means that even though the dialog box still says 'Image Size' at the top, it is now basically the Image Resample dialog box with the checkmark. All of the variables in both the Pixel Dimensions and in 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.
There are also a few 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 not checked. Scale Styles is grayed out because it's only an issue when the number of pixels in an image is being altered. Since the pixels number of the image remains the same with Resample Image unchecked, the Scale Styles is not needed.
Constrain Proportions is grayed out when Resample Image is unchecked since you no longer have the option of changing the number of pixels in the image. This results in the proportions of the image being fixed. An image is 40 pixels wide and 20 pixels in height, regardless of how large or small it is printed, the width will always be twice the size of the height. If the width value in the Document Size section is changed, both the height and the resolution values will also change. Change the height value and the width and resolution values will change. Change the resolution value, and the width and height values will change. They all work together to adjust the image. The only change that can be made now is how large or small the image will print. You accomplish this by entering new values for the document size or by changing the resolution. The Constrain Proportions option is also not needed when all you are doing is resizing the print size of the image.
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
Now comes some big words. "Bicubic" and "Bicubic Sharper" are what is called "interpolation algorithms". All this boils down to is how the hotoshop program handles removing pixels when you resample the image to a smaller size, and how it handles adding pixels when you resample the image to a larger size. In Photoshop CS2, there is another option added called "Bicubic Smoother." Knowing when to use which option can make a big difference with image quality, but can be remembered with a basic rule as follows: Bicubic Sharper - Use this option when resampling your image smaller for best image quality Bicubic Smoother - Use this option when resampling your image larger for best image quality Bicubic - Not used as much with Bicubic Sharper and Bicubic Smoother being available These options will be grayed out here because they only apply to 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 your image will print (the Document Size). Image resampling - Physically changes the number of pixels in your image (the Pixel Dimensions). Resample Image - Option at the bottom of the Image Size dialog box controlling if you are resizing or resampling an image. Checking the Resample Image , 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 primarily 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:
Did you enjoy this article? Interested in learning photoshop fast? Well now you can by reading this free Guide...what are you waiting for?
---------------------------------
Title: Photoshop Tutorials Work...Resizing vs. Resampling
Author: David Peters
Keywords: Learn Photoshop now,photoshop guide,learning photoshop,get photoshop,software help,internet,editing photos using photoshop,photoshop,photogrpahy,hobbies,photoshop tutorials,learn photoshop fast,photoshop,adobe photoshop,photo shop
Word Count: 1407
Category: Arts & Entertainment:Photography
---------------------------------
No comments:
Post a Comment