Adobe Photoshop CC Image Size and Resolution

Pixels and Bits

Bitmap images are made up of individual pixels (picture elements) of information placed on a grid, which a computer understands.

Resampling

Photoshop's process of determining which pixels can be deleted or added, with least effect on the image, in a process called interpolation. resampling down to a lower image resolution deletes pixels but usually retains image quality.

Screen Output

Screen output is intended for websites, email, video, or small screen presentations. because the output is another computer screen, the image resolution can be close to the monitor resolution.

Document Size

The dimensions of the output image, where image resolution is measured in pixels and document size is measured in inches. Monitors can only display at the monitor resolution, regardless of the image resolution.

Resampling in Photoshop

When the resample image option is selected in the image size dialog box, the dimensions fields and the width and height fields are linked: increasing a value in any field will add pixels to the file decreasing a value in any field will delete pixels from the file.

Resampling While Cropping

You can change the resolution while cropping an image: 1.) Click the crop tool 2.) In the options bar, click on the second pop-up menu, and choose W x H x Resolution. 3.) Experiment with different image dimensions, preset crop options, and resolutions by typing values on the options bar. 4.) Adjust the crop handles to define the crop boundaries. 5.) Press Return/Enter to crop.

Resolution and Output

You've probably experienced one or both of these situations: Some images look great onscreen but are broken up and "pixelated" when printed. Most email and web images open quickly, while some take forever to download and open. If you suspect a connection, you are right: The connection is called image resolution, and it's different for different output types.

Print Output

intended for desktop printers or commercial printers

Printer Resolution

measured in ink dots per inch (dpi) on the page, monitor units are pixels per inch (ppi)

Vector Graphics

not made up of pixels

Monitor resolution

the number of pixels a monitor can display per inch (ppi)

Image Resolution

the pixel density of an image, measured in pixels per inch (ppi) of an image. Image resolution is closely related to image file size, measured in kilobytes (KB) or megabytes (MB)

Photoshop's Image Size Dialog Box

use the Image Size dialog box to alter the dimensions or resolution of a file. When the resample image option is not selected: The width, height, and resolution fields are linked (note the chain icon) If you change one value, such as resolution, the other two values change automatically. The dimensions values stay the same; no pixels are added to or deleted from the file.