articles/Postproduction/matterscale-page1

A Matter of Scale And Getting Outo of a Fix - part 1 of 1

Published 01/02/2006

matterscale-01.jpg

Up-scaling of images is a topic which occurs at seminar question times (along with sharpening) on many occasions. For the run-of-the-mill stuff Photoshop does a first-rate job so why invest in a bespoke program, which is an additional cost?

Ultimate quality is one consideration. Even if your client is a visual illiterate, it is sometimes beneficial to be able to say "this image has been up-scaled with the best software algorithms known to man"! The stock libraries have been calling for this approach for some time, even specifying the software to be employed.

We had the classic dilemma in this issue. Arthur Rainville had sent decent-sized images but we decided we would like to spread one of them right across the page. This involved scaling from 76mm x 115mm up to 210mm wide and over 300mm high, a scaling of almost 4x on area. Did we allow InDesign to scale it, do it in Photoshop or go for a specialist program? Like all cautious cowards we went for Size Fixer but being of a curious turn of mind we could not resist going back and looking it over from Photoshop as well. We also proofed the spread to be absolutely sure.

Key features

SizeFixer uses military-grade deconvolution maths to do its sums. For best results it is recommended that you start with an unprocessed file, usually an uncompressed TIFF. In-camera sharpening should be turned off and if SizeFixer can get at the camera meta data so much the better, it will exploit this to its advantage. One downside to the maths is that a typical scaling may require up to 100 billion operations on the computer, which will take a toll on the time to do the job. This can extend to an hour or so depending on the computing power available.


In Use

SizeFixer has been accused of being a bit slow on the uptake (up to 5 minutes). For the record, our image from Art Rainville (3.5MB) loaded in 1.8 seconds - no problem for a dual core processor then! A preview of the up-scale from 3x4.5 to 8x12inches appeared in about 1 second and a standard up-scale took 11.9 seconds to process.

A super resolution preview at "very good quality" took 2m 49s to complete. Interpolation of the upsized image started at an estimate of 21 minutes, fell to 10minutes during processing and actually took 7m 29s (on a 3800GHz, dual core Athlon Processor and 2GB of DDR400 RAM). There are obvious benefits to having a machine with plenty of grunt for these types of operation.

One of the unintended consequences of SizeFixer up-scaling is the loss of the colour profile. Initially we scaled an sRGB file and then mistakenly used our default Adobe RGB workspace when we opened the file to convert it to CMKY. This bumped up the saturation - you need to watch for this, depending on your workflow.

For comparison we scaled the same image in Photoshop using bicubic interpolation. This took 7 seconds. We also tried bicubic smoother. In general the Photoshop scaled images were a little smoother and softer, with the grain not being exaggerated. It is doubtful if you would spot the difference if you could not make side-by-side comparisons.

In need of a sterner test we next attempted a scaleup level that had actually been performed on one of liverpoolwaterfront.com's images for the University of Liverpool. That image (of Paul McMullin's) was scaled to 27 feet before being placed on the wall of the new common room. Working on a similar file (shown) the original was 113MB; 66"x15" @ 200ppi. The scale factor, to 27 feet, was just about 5 fold, giving a 2.77GB file. Rather than grind the computers for an hour or two we took a 6MB snippet out of the original 144MB and worked on that. A comparison is shown between interpolation in Photoshop and SizeFixer without any additional sharpening being applied. The differences are subtle and either would provide a saleable print.

FINAL THOUGHTS

This reviewer remains unmoved by all the talk of Fourier transforms and deconvolution maths, preferring to look at prints and images. By the time the image gets to the page some of the claimed advantages are lost and even though you see some benefit in a Photoshop file blown up to 1600%, the reality is less cut and dried. However it cannot be escaped that some stock image companies demand that you use these methods for scale up so there is no dodging it. SizeFixer SLR (limited to a maximum A1) is £175.07 inc VAT SizeFixer XL (unlimited scale up) is £292.58 inc VAT see www.colourconfidence.com www.fixerlabs.com


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1st Published 01/02/2006
last update 06/11/2019 11:07:08

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