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August 17, 2021

This has easily been the longest sale we've ever had on Acorn - since March 17th!

But if you've been holding out on buying it for some reason, now is the time to purchase. The 50% off sale will end Monday, August 23rd, and the price will double from $19.99 up to $39.99 USD.

The bundle discount will still be available though. So if you buy multiple copies (or multiple apps), you can save some cash. Or buy now and save even more.

April 29, 2021

Update (May 25): Security Update 2021-003 Catalina was released by Apple, and has the required fixes in it to enable Acorn to work correctly again.

Update (May 2nd): Acorn 6.6.5 and Retrobatch 1.4.4 are out for anyone who has downloaded or purchased the apps directly from Flying Meat.

These releases fix most of the problems introduced by the security update, but Flood Fill, Instant Alpha, and the Magic Wand tools are still broken in Acorn. The App Store version of Acorn has not been updated because there's no way to have a new version distributed once it's been removed from sale (even if it is put back on sale, because I tried that and it's not working). Retrobatch was never in the App Store, so it was super easy to get an update out to everyone.

Acorn and Retrobatch are not the only apps impacted by this problem, and I'm hopeful that Apple will be releasing a patch which fixes this in the near future. It could still be a matter of weeks though, so please sit tight until then. The right people inside Apple are aware of the problem, so I'm sure it will be a temporary (though very very unfortunate) issue.

A few days ago on April 26, 2021, Apple released Security Update 2021-002 Catalina for anyone running MacOS 10.15.7.

This security update unexpectedly breaks OpenCL, which is a framework from Apple used for processing images. Other Apple frameworks such as Core Image use OpenCL in some situations. In those cases Core Image no longer works correctly.

The latest release of Acorn, version 7, no longer uses OpenCL by default for processing images. So if you've upgraded to Acorn 7 you're safe.

The Apple security update has broken Acorn versions 6 and lower. Any files saved in these versions of Acorn will end up empty. The update also breaks adding new layers, painting, just about anything to do with processing pixels in previous versions of Acorn.

Retrobatch is also impacted if you use any nodes that process images through Core Image.

While I'd love for everyone to take this opportunity to update to Acorn 7 as a fix, I realize that's not always the best solution and in some cases, not possible.

I'm currently investigating a fix for this, and I have a beta for anyone who is impacted by this to try out.

Acorn 6.6.5 beta:
Retrobatch 1.4.4 beta:

I don’t have any updates for Acorn 4 or 5. Unfortunately, those products are too old to be updated further. My hope is that Apple will revert their breaking change, so that Acorn 4 and 5 can once again work as expected on MacOS 10.15.7. However, if you don’t wish to wait, upgrading to version 7 is the way to go.

Here's the technical version of things as I understand it at this time.

The "Security Update 2021-002 Catalina" has broken Apple's OpenCL framework. Core Image, another framework by Apple and one that Acorn relies on heavily, uses OpenCL to process images when its renderer is set to "software" mode (the other mode is to use the GPU). Core Image tries to use OpenCL and then fails, so all images come out empty.

The quick fix is to tell Core Image not use the software renderer, and then Core Image will move everything to the GPU for processing and use Apple's Metal framework instead of OpenCL — for most cases. I think there is still hardware out there that can't use Metal, so it might fall back to OpenCL in that case.

The Acorn and Retrobatch betas above force Core Image operations to run on the GPU instead of the CPU if it detects you're running on 10.15.7. This will have an impact in various areas such as performance and possibly rendering. I've not done extensive testing so I'm not sure what the fallout from this change will be (though I know it will be there).

It's easy enough for me to pass out a beta and eventually a final release to anyone who purchased Acorn 6 directly from Flying Meat. However Apple's App Store has no mechanism for updating an app that's no longer for sale, and I don't know how to get this fix out to them. (Side note: Acorn 6 is actually marked as available for sale from my end in App Store Connect …but it's nowhere to be seen in the actual App Store. I've never been able to figure out why, and it's been this way since I released version 7.)

It's a big mess.

So why isn't Acorn 7 impacted by the security update? I spent a bunch of time last year getting Acorn 7 to run on the GPU. Targeting Core Image to use OpenCL was deprecated by Apple and it was a good time to stop using it. I was also able to do this because I dropped support for older versions of MacOS where Metal and OpenGL weren't quite accurate enough for Acorn.

Acorn 7 does have the ability to target the software renderer if you mess with the right preferences, but that's not the default setup for Acorn, and I haven't had any reports of people running into the issue (yet).

Nothing in the release notes for the security update mentions OpenCL. I'm baffled and completely in the dark as to what the changes were or why they were done. I've filed a bug report with Apple (FB9091798) and pinged some folks on the inside, but I don't know anything more than that.

March 19, 2021

Acorn 7, our image editor for humans, is out. It's currently on sale for $19.99 (50% off), directly from us or via the App Store. After the sale, the full price is moving up to $39.99 from $29.99. So unless you feel like giving me more money later on, now is a good time to buy it.

So what's new? Here's a casual overview of some things I find interesting with this release.

Visually, the most striking difference is the new unified windows. Acorn 7 has all the floating palettes placed together in the same window as the canvas (and if you prefer floating windows, we've got a pref for that). Unified windows have been a major feature request for a number of years, and I'm super happy to finally have it done for everyone.

It's nice. The same shortcuts work as before - the tab key will hide the inspectors, and ⌘⇧F will bring up the filters inspector as always. Pressing the f key will throw the window into full screen, and now the canvas isn't covered up by the floating palettes.

Acorn 7 is optimized for Apple M1 Silicon. The previous version of Acorn ran pretty well in the M1's emulation layer, Rosetta, but now Acorn 7 is natively built for the M1 which bumps up the speed. Beyond that, a bunch of filters were re-written in Apple's Metal GPU shading language, and I also managed to discover some other Metal optimizations which made Acorn's canvas drawing run quite a bit smoother (As an aside, I was very happy about this. While researching this problem I encountered forum questions posted by myself on this very topic from years ago. It always feels weird when that happens).

The Flood Fill, Instant Alpha, and Magic Wand tools all use a brand new multi-threaded seed fill routine I wrote and optimized on the M1 as well. Super geeky side note: as part of the debugging process when I was coding it, I had each thread draw different colors into a mask which was used for the result. On Intel, each color had a mostly equal representation across the mask. But when I was testing it on the DTK, which has two high performance cores and two low performance cores, you saw an imbalance where some colors were overrepresented and others were underrepresented. It was a visual result of the different speeds of the cores, which I thought was pretty cool.

New Perspective Fix & Crop tool. This handy little tool will draw guides on your canvas to help you fix perspective distortions. You simply line up the guides on your image by moving four handy little corners around, and press enter. Your image is then run through a perspective correction filter and cropped to the appropriate area.

I didn't think much of this feature at first, but I'm pleasantly surprised at how well it's being received. Props to for Kirstin pushing for this feature to be included.

Acorn 7 also has a new color picker. I've been wanting to do this for years, because the system color picker has been nothing but problems for me on account of its inability to set and stick with a specific color profile. For instance, if you have an image open in sRGB but you sample a color from the screen using the system picker, Acorn has to jump through hoops to convert it from the screen's color profile (which most certainly is not what the image is) and then into sRGB, and also keep the color picker informed about this profile change. And then I'd get support questions asking why colors were shifting ever so slightly, and I always hated answering those emails because to understand what's going on requires a lot of base knowledge about profiles and such, and well… it was a bother.

I could write pages and pages of other problems I encountered- but I'll spare you the details. Obviously, I had all these issues in mind when making the new picker, so it only ever has a single profile it draws with, and that's whatever color profile is set for the image. It's kind of nice just side-stepping all of those issues now. It was fun, in a strange way, writing the color picker. I don't consider it finished either, as I think there are a ton of other fun things I can eventually do with it.

OK, what else? The Export window is Über! (Acorn doesn't actually call it "Über" anywhere- I just think it's a good description of what it is now). I combined the previous web export window and the regular export save dialog into a single interface. So you get a nice preview, information on how big the file size is, as well as toggling between what you had previously and what it currently looks like. And I've even added animated GIF support when exporting. So you can open up an animated GIF, apply some filters or add some frames, and export it back out.

There's a new Navigation & Zoom Inspector which will probably be familiar to you if you've used other image editors in the past. It's a good way to quickly pan around your image when you're zoomed way in.

New Command Bar, which is sort of like Spotlight, but geared towards Acorn's commands and documentation. To search Acorn's docs, type "h" followed by a space, and then whatever topic you're interested in. Or, if you just want to quickly use the new Perspective Fix & Crop tool, you can type start to type "pers" which will filter up any commands that have those letters. Perspective Fix & Crop will be first, so you can hit enter and then you're in that mode quickly.

One nice thing about the Command Bar is that I can also include other random oddball things in there which don't necessarily deserve a menu item by itself. For instance, there's a toggle in there to switch Acorn into Dark Mode or to Light. There's an entry to quickly switch to pixels for the ruler, or fill the current selection or layer with the stroke color, or capitalize any currently selected text. I get requests all the time for cool little ideas (just today I got someone asking for the ability to pull the alpha channel out into it's own layer). I've always shied away from these ideas because I want Acorn to be approachable, and having too many options in the menus can be a big turn off. But if they could be tucked away in the Command Bar, ready at your finger tips if you know it's there? I think that might end up being a very powerful thing if I can solve the discoverability problem (which might just be a matter of making sure everything is documented).

That's just a few of the new things in Acorn 7 I think are fun. As always, the full release notes are of available. There's a bunch of little things in there that are worth knowing about, so check them out. And of course, download a trial of Acorn today.

November 10, 2020


The current version of Acorn (v6.6.2) is fully compatible with MacOS 11 Big Sur on Intel. We're about ready to release version 6.6.3 which fixes some cosmetic issues with MacOS 11, so look for that in the coming days.

A universal binary of Acorn for Apple Silicon is taking a bit longer than I originally planned (2020 is the gift that keeps on giving for us). For the most part, Acorn 6.6.3 runs fine in Rosetta (the translation layer that the new ARM based Macs use to run non-native Mac apps). However a couple of the tools* aren't compatible with Rosetta, so we've had to do a complete rewrite for those.

Update: Apparently these tools decided to magically start working again in the latest Big Sur release. I'm not sure how or why, but- hey, thanks Apple for fixing that.

The good news is I took a fresh look at those tool backends when rebuilding it, and I'm happy to say the newer versions are quite a bit faster.

The plan is to have a public beta of a Universal Binary of Acorn in the near future, so if you have one of the new Apple Silicon based Macs you'll be able to kick the tires on it at full speed.


You can download an Apple Silicon ready Universal Binary for Retrobatch right now. This beta version (v1.4.3) is fully compatible with MacOS 11 Big Sur as well. We hope to have the final release ready in a few days.

Apple Silicon Mac Thoughts

I'm pretty excited about the new Apple Silicon Macs. I've been developing on one for a number of months now, and I'm very happy with a number of aspects of it, most especially the shared memory between the CPU and the GPU. This has enabled various tools (such as brushes) to speed up dramatically in Acorn, without me having to do anything to support it. It's been pretty great.

* The specific tools we had to rewrite for Acorn are Flood Fill, Instant Alpha, and Magic Wand selection. These tools were originally written in OpenCL targeting the CPU, which unfortunately isn't supported in Rosetta. Update: Maybe they are now shoved through a compatibility layer, and sacrifice speed for working?

May 28, 2020

Acorn 6.6 is out. You can update to this release via the App Store as or the Acorn ▸ Check for Updates… menu if you bought it directly from us.

Originally this was going to be a bug fix release but I kept on adding useful things and it snowballed into a feature release. As usual, the full release notes have all the details about what was updated.

The main new features are with the Shape Processor. If you're not already familiar with the shape processor, it's a neat ability Acorn has to take shapes on vector layers and pipe them through a series of actions, similar to how Automator or Acorn's bitmap filters work. Only instead of working on pixels, the processors will alter the shapes by scaling them or moving them around, or changing colors or blend modes. There's even a processor which will generate shapes for you- so if you want your canvas to fill up with hundreds of stars, you can do that.

Acorn 6.6 adds new processors which let you set the stroke, fill, and blend mode of your processed shapes. You can now also flip your shapes and even shift colors.

Chaining these processors together can get you some neat looking images. You can make interesting desktop backgrounds, as well as textures for your photos. Or if you just need a bunch of hexagons arranged in a circle, that's just two processors stacked together.

Have you made something interesting with the Shape Processor? I'd love to see it either via Twitter (I'm @ccgus) or via email.

There are of course the usual bug fixes and other minor details. And if you don't already have Acorn, a no-strings attached free trial is available on our website. Try it out, and we're always looking to hear from you about feature requests, thoughts, and anything else.

March 31, 2020

I've just typed the magic commands* and let the servers do their thing and now Retrobatch 1.4 is loose on the world.

There's a couple of interesting new features in this update I'd like to call out. First up is JavaScript expressions in Retrobatch Pro. Various nodes in Retrobatch which allow you to set the size or length of a value (such as the Crop, Border, Gradient, Adjust Margin nodes) now have an option of running a little snippet of JavaScript code to figure out the value. This is a super powerful feature, which you can read about in our JavaScript Expressions documentation

Let's say you have some images of varying sizes, which are all at 480 x 380 or smaller, and you want them to expand to meet that size. But- you only want it to grow evenly on either side of the image, but you want to keep a baseline so only transparent area is added to the top of the image, and the bottom stays in the same spot. This little picture of the new Adjust Margins node shows how this can be done:

Yes, this is an oddball (and very real) case- but there's a billion of these little oddball cases out there. With the new JavaScript expressions support, these small but hard to do scenarios are now super easy.

And yes, all of the JavaScript support in Retrobatch now sits atop FMJS, which any developer can use to build similar support into their apps.

What else is new?

File numbers with leading zeros for the Write node. You can add (and it's case sensitive) $FileNumber04$ in the File name: field of the Write node to have the file number of your image written out as part of the name, with a padding of up to 4 zeros. If you'd like to pad that number to 6, you would enter $FileNumber06$, and so on.

The Mask to Alpha node got a new "invert colors" option. Normally Mask to Alpha will convert the black areas of your image to transparent, and the white to opaque (with gray somewhere inbetween). With the new Invert Colors option, Mask to Alpha will now convert the white areas of your image to transparent, and keep the black opaque. This is great if you are scanning in line drawings from your own artwork, and want to make the backgrounds transparent.

This request comes up a lot in Acorn as well. Previously you'd have to add an Invert Colors node (or filter for Acorn), then the Mask to Alpha, and then Invert Colors again. Now it's just a checkbox in Mask to Alpha, which is super easy. I've also added an update to the same filter in Acorn for the next release. You can grab a preview of it from here.

And finally for my short list, you can now make a droplet which doesn't take any files. Why is this useful? Well, imagine you have a workflow that reads an image from the clipboard, resizes it to a specific width, and then writes it back to the clipboard. Now you can make a little droplet to do just this. Just a double click from the Finder (or a single click from the Dock) and your workflow is run.

The full release notes for Retrobatch 1.4 are available in the usual place.

* ./bin/ -e 1.4

October 7, 2019

MacOS 10.15 Catalina was just released, and we're happy to let you know that both Acorn 6.5.1 and Retrobatch 1.2 are compatible with it.

And to celebrate the release of Catalina, we're discounting Acorn by 50% for a limited time. So if you haven't upgraded yet, now is a good time.

April 1, 2019

We're happy to announce that Retrobatch 1.2 has now been released, which is a free update for all owners of Retrobatch. Highlights of this release include:

  • Create animated GIF and PNG images with the Animated Image node. When using Retrobatch you can load in a folder of images and produce an optimized animated image with options for setting the frame rate, format, as well as letting the image loop or not.

  • New nodes including "Round Corner", "Image Grid", and "Limit". We've also added improvements to the Write node allowing you to write back to the original processed image.

  • Droplet support (Retrobatch Pro). Turn your workflow into an an application which you can drag and drop images onto. The droplet can work anywhere an application normally would, even in the Dock.

  • Write Plug-Ins using JavaScript (Retrobatch Pro). Using the combined power of JavaScript and the native to MacOS Cocoa APIs, you can make and distribute new plugins for Retrobatch. Got an idea for a plug-in and you want to use Core Image to make it? Or maybe you want to use Core Graphics to add some funky text to your images? Now you can do this with JavaScript and Cocoa.

The full release notes are available, as well as information on bug fixes we delivered in this update.

As always, we're always listening for feedback and feature requests. And don't forget to head over to the Retrobatch community formus to chat with us and other Retrobatch users.

January 9, 2019

Acorn 6.3 is available, and the full release notes are up as well.

Here's what I think is awesome in this release:

Portrait Mask Support. If you have an iPhone running iOS 12 (and can take Portrait photos), Acorn will now detect the Portrait Matte from those images and turn it into a layer mask. The Portrait Matte is the image data which enables blurring in the background, or other fancy camera tricks. This means you can use this matte to erase and add fancy backgrounds or custom blurs for your image, all within Acorn.

Other Mask Features. You can now drag and drop masks from the layers list into another layer, or copy it out as a new layer. When exporting layers you now have an option to apply the mask on export, or just write it as an additional image along with everything else. There are a number of new shortcuts when dealing with layer masks as well.

Brush Stuff. If you're running MacOS 10.13 or later, you get a performance boost when brushing (painting, smudging, cloning, etc…). This is especially noticeable when brusing on deep color images.

I've also added options to the brush palette for adjusting flow, softness and blending. In addition to all this, there's a bunch of new brushes under the "Basic Round" category which are designed for the new brush engine.

Other Stuff. There's other good things including improved PDF export, various MacOS Mojave UI fixes, additional speed improvements with with deep images, and more. And as always, it's a free upgrade for anyone who has already purchased Acorn 6.

September 27, 2018

On Monday I flipped some switches on the FM servers and Acorn 6.2 was released to the universe. You might also remember that Monday a little known operating system from Apple was updated, which includes a neat new feature known as Dark Mode.

I think Acorn looks pretty good in Dark Aqua, especially the icon refresh from Matthew Skiles.

To celebrate the new release, we've put Acorn on sale for 50% off. So go grab it at the insanely low price of $14.99. If you haven't already upgraded from previous versions of Acorn, now is a good time to do so.

We've also packed a bunch of little changes, bug fixes, and compatibility with Mojave in there. And of course, there's more to come in the future as always.