Acorn 6 full review
There's a theory that most popular apps used today, such as Microsoft Word or Adobe Photoshop, reached their zenith a decade or two ago. Since then the folks behind them have been packing in new features but ultimately it's a game of diminishing returns and, for most users, the apps are as good as they ever were.
In many ways Acorn feels and even looks like a snapshot of Photoshop all that time ago - with a selection of the more modern and useful Photoshop tools mixed in too. You get all the tools that made Photoshop so damned useful in the first place, such as levels and curves to adjust an image's brightness/contrast, as well masking and layers, and various filters - not to mention a toolbar with standard brush and selection options.
All of these are indispensable when editing images. However, while you avoid the modern-day cruft, you also miss out on the rare useful innovations that have come along, like the heal and patch tools, or advanced selection tools that let you select by colour range, amongst other things. If you make heavy use of these then their absence in Acorn can be frustrating.
Early in our testing of Acorn we encountered a strange issue whereby drawing tools (including the clone tool) were very laggy and slow to the point where they were essentially unusable. For example, attempting to draw a curve would instead draw an angled line. Other tools within the app, such as filters, worked fine and were applied speedily.
The app comes with a free two-week trial and we'd advise you to make use of that before purchase to ensure your system doesn't suffer from this issue, which is almost certainly a bug, and our earlier tests a year or two ago of Acorn 4 didn't have this issue.
(Flying Meat, the makers of Acorn, got in touch on 27 Jan 2018 to tell us the slowdown is "caused by issues in [macOS] 10.13, and we've got fixes in 6.0.4, as well as a complete solution in 6.1 which should be out soonish.")
As you might expect some tools are not where you'd expect if switching from Photoshop. To adjust the colour saturation and vibrancy of an image, for example, you'll need to use an entry on the Filters > Color Adjustment menu. Additionally, effects and filters are applied as soon as you select and adjust them, without the need for an intermediate stage wherein you click the Apply or Cancel buttons. However, within 5 or 10 sessions using Acorn you'll get used to this.
Acorn is also a capable drawing tool should you want to create artwork from scratch. There's a brush designer tool, as well as the ability to import brushes designed for Photoshop. The shape generator tool does exactly what it says on the tin.
Despite Acorn's somewhat retro feel there's support for RAW images in that the app uses macOS's own import filters, which are actually pretty comprehensive in their inclusion of most makes and models. Images are opened in a special RAW import window that lets you adjust things like exposure and colour temperature, although notably missing are any tools to correct for lens distortions, as you'll find with most RAW processing apps. Once you click OK the image is then opened in the main Acorn editing area, after which you can save it out in the usual file formats - but not, alas, as a RAW image.