Image Resolution versus Image Size What resolution should ...

Image Resolution versus Image Size Resolution is determined by the number of pixels, or dots, in a linear inch. An image with a resolution of 72 has 72 dots in a linear inch. The higher the resolution of an image, the better the quality of image you have.

The image size is determined by the resolution multiplied by the height and the width of the image. Your height and width will be determined by how you received the image, be it a camera, scan, etc.

What resolution should I use?

Output Device Desktop color inkjet Professional Photo lap printer Desktop Laser Printer Large format inkjet Magazine quality Screen images

Optimum 330 dpi 300 dpi 170 dpi 150 dpi 300 dpi 72 dpi

Acceptable Resolution 180 dpi 200 dpi 100 dpi 120 dpi 225 dpi 72 dpi

Resizing an Image for Print

Digital Camera file sizes will vary. The size of the image will most likely be huge in dimension; too large for normal size printers. Let's resize and image for Print.

File, Open and select the file: AK 240dpi.jpg

From the Image menu, select Image Size

The Size of image is 46.0M The dimensions are 20.5" x 13.6" Resolution is 240 dpi

Photoshop ? Resizing Images Colorado State University Computer Applications Training ?

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Resample Image Simply put, resampling an image changes the pixels within the image, by either adding or subtracting pixels. Resampling will alter the pixels in the image, but will not change the size of the image.

If you do not want to alter the pixels within the image, make sure you uncheck Resample Image:

Changing the Resolution Without Changing Pixel Data:

From the Image Size dialog box, deselect Resample Image

Result pixel data is grayed out, pixel data is locked, which means your quality is locked.

File size will not decrease, Image dimensions and pixels will change.

Change the resolution to 360.

Notice the document resized and the pixel data did not change.

Tip: Your eyes are not going to see the difference between 240 and 300 on the screen, or between 72 and 360 for that matter.

Notice the file size did not change.

Change the resolution to 200

The image resized File size is still the same

You can print the image from Photoshop or save it as a Tiff and print it later.

Photoshop ? Resizing Images Colorado State University Computer Applications Training ?

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How do I resize and image for the Web or eMail?

From Photoshop open the file: AK 72dpi.jpg

Select Image, Image Size

Notice the size of the image. 3.66 M is kind of large for an email or a web page.

Leave Resample checked or turned on.

We do want to affect the pixels and reduce them in order to reduce our file size.

Email: 320 x 240 pixels is a good size for an image over email

Position the cursor in the Pixel dimensions area of the Image Size dialog box and change the width to 320 pixels. The height will adjust accordingly.

Press Ok.

Notice the image is smaller. Change the zoom level to 100% by clicking twice on the zoom tool.

Photoshop ? Resizing Images Colorado State University Computer Applications Training ?

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Save the File

Size guidelines for email and web Choose File, Save for Web. In the Save for Web window, click on the 2-Up tab on the top of the window. File Format: jpg for photo Quality: Choose High for email quality You can click on the quality dropdown to adjust your quality as needed, to make your image larger or smaller. You will see the changed on the bottom of the screen. Press Ok and Save.

Photoshop ? Resizing Images Colorado State University Computer Applications Training ?

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How to Resize an Image from the Web for Print?

You will find images on the web that you might need to print.

Caution: look at copyright data.

Images on the web are typically low in resolution and are not set up for print quality. Prior to printing the image, you need to review the image and change its resolution.

Remember, when you increase your resolution, your physical image size will get smaller.

File, Open, CSU from web.jpg Select Image, Image Size

The Image is very small, but it is 4" x 3"

We don't want to alter the quality of the image. Instead we want to increase the resolution, so the pixels will be packed more closely went sent to the printer.

Deselect the Resample image.

Notice the pixel dimension area is locked.

Change the resolution from 72 to 150.

Notice the width and height adjusted automatically and it's smaller.

Bottom line, there is not a whole lot of flexibility when trying to make a web image higher in resolution for print. The physical size of the image will have to decrease in order to get print quality.

Photoshop ? Resizing Images Colorado State University Computer Applications Training ?

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