Page 16 - Adobe Photoshop and Dreamviewer 2021

Open and Resize an Image
Every raster image has a defined, specific resolution that is established when it is
created. If you scan an image to be 3″ high by 3″ wide at 150 ppi, that image has
450 pixels in each vertical column, and 450 pixels in each horizontal row. Simply
resizing the image stretches or compresses those pixels into a different physical space,
but does not add or remove pixel information. If you resize the 3″ × 3″ image to
6″ × 6″ (200% of the original), the 450 pixels in each column or row are forced to
extend across 6″ instead of 3″, causing a marked loss of quality.
The effective resolution of an image is the resolution calculated after scaling
is taken into account. This number is equally as (and perhaps, more) important as
the original image resolution. The effective resolution can be calculated with a
fairly simple equation:
Original resolution ÷ (% magnification ÷ 100) = Effective resolution

If a 300-ppi image is magnified 150%, the effective resolution is:
300 ppi ÷ 1.5 = 200 ppi

In other words, the more you enlarge a raster image, the lower its effective
resolution becomes. In general, you can make an image 10% or 15% larger without
significant adverse effects. The more you enlarge an image, however, the worse the
results. Even Photoshop, which offers very sophisticated formulas (called algorithms)
for sizing images, cannot guarantee perfect results.
Effective resolution can be a very important consideration when working with
client-supplied images, especially those that come from consumer-level digital
cameras. Many of those devices capture images with a specific number of pixels, rather
than a number of pixels per inch (ppi). In this exercise, you will explore the effective
resolution of an image to see if it can be used for a full-page, printed magazine ad.

1. Download Movie_Web21_RF.zip from the Student Files web page.

2. Expand the ZIP archive in your WIP folder (Macintosh) or copy the
archive contents into your WIP folder (Windows).
This results in a folder named Movie, which contains all of the files you need for this
project. You should also use this folder to save the files you create in this project.

If necessary, refer to Page 1 of the Interface chapter for specific information on
expanding or accessing the required resource files.

3. In Photoshop, choose File>Open. If necessary, click the Your Computer
button in the bottom-left corner of the dialog box to show the system-
standard navigation dialog box.
The Open dialog box defaults to show the last-used option, so you might see the
Cloud Documents pane, which is used to access any files that have been saved directly
into your Creative Cloud (CC) account.
In this project you are working with files on your local computer (or other local drive),
so you might need to click the Your Computer button to access the system-standard
navigation dialog box for opening files.

28 Project 1: Composite Movie Ad