I’m a professional graphic designer. 4 years of college and 3 years of job experience have not been able to explain this.
Why is it that two images with the same pixel dimensions can be different resolutions? As I understand it, a pixel is one dot of color in a larger image, and resolution is a measurement of pixel density, so two images displayed at the same size with the same number of pixels should always be the same resolution.
I created an image for an email signature at about 1200 pixels wide. When implemented, the computer scaled it down to 299 pixels wide so it would fit, and it looked perfectly crisp and clear. This part makes sense to me.
To minimize the load time and storage for the image, I scaled it down to 299 pixels wide in Photoshop – exactly the same size it was in the signature – but it came out far lower resolution than it was on the email signature.
How can this be? This isn’t the first time I’ve encountered this issue. In fact, I run into it so often that I normally avoid using pixels as a measurement for images entirely. I’ve googled it many times with no solid answer. I struggle to understand why we even bother measuring images in pixels if the measurement doesn’t mean anything.
In: 6
A device can pack more pixels in a given area leading to more detail. A basic monitor might have around 83 DPI, while a small but sharp display can have 120 DPI or more. Most images carry a tag that describes the relationship between pixel count and physical size.
Usually an image is displayed on screen 1 to 1 disregarding the resolution. A higher resolution screen would show most images smaller. But some software made for print can actually scale it to take into account the pixel density of the monitor and maintain the intended dimensions of the image (in inches or centimeters). PDF documents usually have the resolution of embedded graphics noticeably reduced, but the elements still line up because they get stretched accoridng to the saved resolution tag.
If you output your graphic with lossy compression, its fine features might be somewhat smudged. But if you have more input pixels the artifacts will also be proportionally smaller and harder to see.
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