Page 18 - Adobe Photoshop and Dreamviewer 2021

7. Choose Image>Image Size. The actual number of
The Image Size dialog box shows the pixels in the image is
number of pixels in the image, as well the most important
information.
as the image dimensions and current
resolution. You can change any value Choose Inches in
in this dialog box, but you should the Width menu.
understand what those changes mean
before you do so.

8. If necessary, choose Inches in the Use this widget to Click and drag in the Note:
menu to the right of the Width change the preview window to
field. preview percentage. show a different area. Press Command-
Option-I/Control-Alt-I
As you can see, this image is currently 37.5 inches wide and 50 inches high, but it to open the Image Size
was photographed at 72 pixels/inch. For most commercial printing, you need at least dialog box.
300 ppi. You can use the principle of effective resolution to change the file to a high
enough resolution for printing.
Note:
9. Check the Resample option at the bottom of the dialog box (if necessary).
When Resample is
The options in this dialog box remember the last-used choices. The Resample option checked, you can use
might already be checked in your dialog box. the attached menu to
Resampling means maintaining the existing resolution in the new image dimensions. tell Photoshop how to
In other words, you are either adding or deleting pixels to the existing image. When generate extra pixel data
this option is turned on, you can change the dimensions of an image without affecting when increasing the im-
the resolution, or you can change the resolution of an image (useful for removing age size, or which pixels
excess resolution or downsampling) without affecting the image size. to discard when reduc-
ing the image size.
10. Change the Resolution field to 300 pixels/inch.
When you change the resolution with
resampling turned on, you do not
change the file’s physical size. To achieve When Resample is
300 ppi resolution at the new size, checked, changing the
Photoshop needs to add a huge number Resolution value adds
or removes pixels.
of pixels to the image. You can see at the
top of the dialog box that this change
would increase the total number of pixels
from 2700 1 3600 to 11250 1 15000.
You can also see that changing the resolution of an image without affecting its physical
dimensions would have a significant impact on the file size. Changing the resolution
to 300 ppi at the current size would increase the file size to nearly 483 megabytes.

Higher resolution means larger file sizes, which translates to longer processing time
for printing, or longer download time over the Internet. When you scale an image
to a smaller size, simply resizing can produce files with far greater effective resolution
than you need. Resampling allows you to reduce physical size without increasing the
resolution, resulting in a smaller file size.
The caveat is that once you delete pixels, they are gone. If you later try to re-enlarge
the smaller image, you will not achieve the same quality as the original file before
it was reduced. You should save reduced images as copies instead of overwriting the
originals.

30 Project 1: Composite Movie Ad