Can you enhance the quality of a low-resolution image?
It’s a familiar scene: a detective asks someone to “enhance” a blurry image on a computer until it becomes clear enough to make out a key piece of evidence. Does this work? Not the way Hollywood does it.
The only way to resize a smaller photo into a larger, high-resolution image without highlighting poor image quality is to take a new photograph or re-scan your image at a higher resolution. You can increase the resolution of a digital image file, but you will lose image quality by doing so. However, there are some measures you can take in Adobe Photoshop to help you increase resolution while upholding visual quality.
How resampling and interpolation affect resolution.
Resampling images in Photoshop means changing their resolutions by adding or subtracting pixels. Resolution is measured in pixels-per-inch or PPI. The more pixels an image starts with, the higher the resolution. Decreasing the number of pixels is called downsampling, which removes data from your image. Increasing the number of pixels is called upsampling, which adds data to the image. When you increase the number of pixels in an image without adjusting the dimensions, you are adding more pixels into the same amount of space and increasing the resolution (or amount of detail) held within each inch. Removing data is preferable to adding it, since Photoshop will have to guess at how any newly added pixels should look.
Choosing the best interpolation method when upsampling.
Resampling of any kind, especially upsampling, can result in poorer image quality. The interpolation method is how Photoshop chooses the colour values of new pixels. Choosing the correct interpolation method can help to avoid unwanted pixelation: