Project 9 - Resizing Images

I haven’t forgotten about Assignment 1 – it’s in hand, and I’ll write about it in a post sometime soon.

Meanwhile, on to Project 9 – resizing images. This was a fascinating exercise, as I’ve not looked at the various options available before. I’ve always gone with ‘Bicubic’, because there’s a note next to it in Photoshop that says it’s best for smooth gradients.

I chose a low-resolution image of a hoverfly to experiment with, as it is packed with detail, and I was hoping that this would make it easier to distinguish between the various upsizing results. Here’s an even lower-res copy, so that you can see what the image as a whole looks like:

Here’s a 100% crop of part of it, followed by full-res crops of versions upsized to 150%.

Nearest Neighbour:

 Bilinear:

 Bicubic:

 Bicubic Smoother:

Bicubic Sharper:

The project instructions indicated that I should upsize using three methods – bicubic, bilinear and nearest neighbour. However, my version of Photoshop also offers two other alternatives – bicubic sharper and bicubic smoother – so I tried these too.

From the images above, it is apparent that the method of upsizing produce different qualities and styles of image. The bilinear method has produced a softer result than the others, whereas the nearest neighbour method has produced an image that is sharper at first glance. Upon closer inspection though, it becomes apparent that there is noticeable pixelisation, and that the ‘halos’ caused by earlier use of the Unsharp mask have become a lot more distinct.

The other three (bicubic) methods have produced similar results, with (predictably!) the ‘sharper’ option appearing most distinct and the ‘smoother’ option giving a softer appearance.

 Of the five methods, ‘bicubic’ seems to me to be of the highest quality. It gives a happy medium between ‘sharp’ and ‘soft’, retaining detail, but without causing noticeable pixelisation. It seems that I have been using the most high quality option all along, although I'll admit that my choice was more due to accident than design!

The bicubic image also produced a satisfactory print, although I think artefacts would start to become noticeable if the method were used to upscale this particular image more than 150%.