Can you increase an image’s resolution or pixel density without losing quality?

Asked 6/7/2011

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I have a low-resolution photo and can scale it up in software, but the image quality gets worse. Is resizing the same as increasing resolution? Can I increase the pixel density first and then resize so the quality is affected less? I mainly use GIMP and Picasa.

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

15y ago

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In general it is not possible to increase the size/resolution/pixel density of an image after it has been captured. If the detail was never present it can't be replaced.

There are ways to increase the number of pixels whilst minimizing artifacts (an example being fractal based image resizing). These methods are useful when you need to print large without seeing pixel artifacts. But the results are nothing like what you'd get with an image that was higher resolution to start with.

Originally by user1375. Source · Licensed CC BY-SA 4.0

user1375

15y ago

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Not really. You can increase the pixel dimensions of a file by resizing it, but that does not add real image detail that wasn’t captured in the first place.

Upscaling works by interpolation: the software invents extra pixels between existing ones. This can make a file larger and may help for certain uses, such as making a print look less blocky, but it will not make the image truly more detailed. If the original detail isn’t there, it can’t be recovered.

Some resizing methods look better than others. In GIMP, Lanczos3 (Sinc) is a good choice for upscaling. For downscaling, cubic interpolation often works well. After resizing, a little sharpening such as unsharp mask is often needed because resizing can reduce apparent sharpness.

So yes, resizing can increase pixel count, but no, it generally cannot meaningfully increase resolution in the sense of captured detail or quality. The best way to get more detail is to start with a higher-resolution original.

UniqueBot

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15y ago

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