Image Size

[ishfaque.b]

1. What is the difference between keeping resample on and keeping it off?

I want to enlarge a picture and make it 300 ppi.

2. When do i need to keep the resample checked or unchecked?

[Mylenium · Accepted solution]

Entirely depends on what kind of effect you want. Resizing images without resampling will simply duplicate pixels (upsizing) or eliminate every n-th one (downsizing) and give that pixely GIF look. Using no resampling sometimes can be useful for graphical elements with large uniformely colored areas, since it keeps edges sharp while resampling is uesed pretty much for everything else. There's no general recipe what's right and what's wrong and you ahven't provided enough info, anyway.

Mylenium

[D Fosse]

A file is just pixels. Pixels have no size - you assign a print size by setting a ppi (pixels per inch) value. Pixels per inch - do the math.

• Resample off leaves the file unchanged, it just changes the assigned ppi value so the same pixels will print larger or smaller.
• Resample on attempts to recalculate the number of pixels in the file according to the ppi value. The key phrase here is attempt, because this will change the original data irreversibly, and you always risk a significant loss in quality.

This becomes much easier to grasp if you sit down and consider what pixels per inch really means. When you understand this, the rest becomes self-explaining.

[Test Screen Name]

By the way, you can't make a  small picture good by enlarging it. Generally pointless. Get a bigger starting point.