How Do I scale up a scanned watercolour painting without losing quality?

Hi,

Scaling up a scanned watercolour painting without losing quality can be challenging, but there are a few steps you can take to minimize the loss of quality:

1.Increase the DPI of the scanned image: If you scanned the painting at a lower resolution, such as 72 DPI, you'll need to increase the DPI to at least 300 DPI for printing purposes. This will add more pixels to the image, which will help maintain its quality when you scale it up.

2.Use Photoshop's "Image Size" tool: Open the scanned image in Photoshop and go to "Image > Image Size." In the dialog box that appears, make sure the "Resample Image" box is checked and choose "Preserve Details 2.0" as the resampling method. Then, increase the size of the image to the desired size (e.g. 96x96 inches), making sure that the "Constrain Proportions" box is checked. This will prevent the image from being distorted.

3.Use Photoshop's "Smart Objects": After scaling up the image, convert it to a Smart Object by right-clicking on the layer and selecting "Convert to Smart Object." This will allow you to resize the image again in the future without losing quality.

4.Apply some sharpening: After scaling up the image, it may look slightly blurry. To help counteract this, go to "Filter > Sharpen > Smart Sharpen" and apply a small amount of sharpening to the image. Be careful not to overdo it, as this can create unnatural-looking edges.

Keep in mind that while these steps can help maintain the quality of the image when scaling it up, there may still be some loss of quality, particularly if the original image was scanned at a low resolution. It's always a good idea to test print a small section of the image at the desired size before printing the entire thing to ensure that it looks good.

Hope you find this Helpful !!

Karthik

At this size 100 ppi is plenty enough. The image size dialog will do that calculation for you and tell you how many pixels you need (not at my machine to check right now).

I agree with @D Fosse – always scan at the highest native optical resolution (not interpolated resolution).

With resampling turned off, Image Size will indicate the uninterpolated resolution at a given physical print size.

All that being said, you are asking for 11" at a given scanned resolution to output at 96".

First of all - rescan at the highest possible resolution your scanner allows.

What you want is as many pixels as possible in your original file. A digital image file doesn't have a size as such, it only has pixels. That's what Photoshop works with.

Size is a secondary consideration, determined by setting a pixels per inch-number (ppi). This is a measure of pixel density on paper, and thus physical print size.

Yes, you can scale up, but it will almost certainly not look good. Not only does it have to invent additional pixels, but it will also introduce artifacts. Any scaling will in some way degrade the pixel structure, especially if you go up. That's why you want to have as many pixels as you can to begin with.

A modern high-end camera will have about 8000-9000 pixels on the long side. This is usually enough for reproduction at any size - assuming the file is of high quality (otherwise it's wasted). So if you can get a size like that from your scanner, you should be good to go and no scaling should be needed at all.

Other than that, it's impossible to be specific without knowing the pixel size you have, and preferably also see a (cropped) example screenshot from Photoshop, displayed at 100% view.