Adobe ADBCD17648MC Manuel D’Utilisation
137
USING PHOTOSHOP ELEMENTS 8
Cropping, resizing, retouching, and transforming photos
Cropping, resizing, retouching, and transforming photos
Last updated 7/26/2011
Image size and resolution
About image size and resolution
The image size (or pixel dimensions) of an image is a measure of the number of pixels along an image’s width and
height. For example, your digital camera may take a photo that is 3000 pixels wide and 2000 pixels high. These two
measurements have a direct correlation to the image’s file size, and both are an indication of the amount of image data
in a photo.
height. For example, your digital camera may take a photo that is 3000 pixels wide and 2000 pixels high. These two
measurements have a direct correlation to the image’s file size, and both are an indication of the amount of image data
in a photo.
Resolution is the fineness of detail you can see in an image. It is measured in pixels per inch (ppi). The more pixels per
inch, the greater the resolution. Generally, the higher the resolution of your image, the better the printed image quality.
inch, the greater the resolution. Generally, the higher the resolution of your image, the better the printed image quality.
Although a digital image contains a specific amount of image data, it doesn’t have a specific physical output size or
resolution. As you change the resolution of a file, its physical dimensions change, and as you change the width or
height of an image, its resolution changes.
resolution. As you change the resolution of a file, its physical dimensions change, and as you change the width or
height of an image, its resolution changes.
You can see the relationship between image size and resolution in the image size dialog box (choose Image > Resize
>
Image Size). Deselect Resample Image, because you don’t want to change the amount of image data in your photo.
Then change the width, height, or resolution. As you change one value, the other two values change accordingly.
Then change the width, height, or resolution. As you change one value, the other two values change accordingly.
The same image printed at 72 ppi and 300 ppi; inset zoom at 200%
If you need to print at a specific resolution, or if you want to print an image significantly smaller or larger than the
image’s pixel dimensions allow, you can resample the image. Resampling involves either removing or adding pixels to
the image to achieve the desired dimensions or resolution.
image’s pixel dimensions allow, you can resample the image. Resampling involves either removing or adding pixels to
the image to achieve the desired dimensions or resolution.
About printer resolution
Printer resolution is measured in ink dots per inch (dpi). Generally, the more dots per inch, the finer the printed output
you’ll get. Most inkjet printers have a resolution of 720 to 5760 dpi, the latter being the smallest dot size a printer can use.
you’ll get. Most inkjet printers have a resolution of 720 to 5760 dpi, the latter being the smallest dot size a printer can use.
Printer resolution is different from, but related to, image resolution. To print a high-quality photo on an inkjet printer,
an image resolution of about 220 ppi should provide good results. Using a lower resolution, you can print a slightly
larger photo—if you are willing to accept some image degradation. You’ll see a warning if you chose a print size that
causes the photo to print at less than 150 ppi.
an image resolution of about 220 ppi should provide good results. Using a lower resolution, you can print a slightly
larger photo—if you are willing to accept some image degradation. You’ll see a warning if you chose a print size that
causes the photo to print at less than 150 ppi.