Here's a neat little trick you can use in Acorn 7 and later. If you have a single layer you'd like to crop without changing the size of the image (for whatever reason - I know you have one), you can use the crop tool like you normally would, and when holding down the option key when you're ready to make your crop, the "Crop Image" button in the palette will change it's text to "Crop Layer". Clicking on it will trim your layer of unnecessary pixels. You can also double click on the canvas with the option key down and Acorn will crop the current layer only.

You can of course get the same effect using the select tool, using the Select ▸ Inverse menu item, and then pressing the delete key. But our minds all work a little different so it's nice to have multiple ways of doing something.

gus@srv:~/Projects/acorn7/.
$ ./bin/pxbuild.sh -e 7.4.2

That's how a new build of Acorn gets pushed up (mostly). Which means Acorn 7.4.2 is out and available via the Acorn ▸ Check for Updates… menu item, or your local Mac App Store. And I'm feeling slightly lazy so I'm just going to copy and paste the release notes for you:

# New Screenshot Stuff.

• Delayed layered screenshot: Hold down the option key when choosing the Image ▸ New Image from Layered Screenshot menu item and Acorn will wait an extra 10 seconds before taking the screenshot. This is awesome if you want to quickly switch to another app and open up a menu item.
• New Shortcuts action to take screenshots. Layered or not, with or without shadows, only for a certain app, and even with a little delay. MacOS 11+ only.
• New AppleScript command "screenshot" which you can use to take a layered screenshot, with various options including an option to only capture a specific app. Here's an example: tell application "Acorn" to screenshot app "Mail" delay 4 with layers and hiding shadows. You can also use "bundle identifier" instead of "app" to target a specific app name.

# Fixes and Other Stuff Pertaining to the Clone Tool.

• New option "Hide clone source widget" in the palette, which does exactly what it says on the tin.
• Pressing the shift key now shows the correct stamp preview.
• Other little tweaks, such as updating the hint text correctly.

# More Fixes

• Fixed a problem where the quick mask tool wouldn't work correctly on M1 & M2 Macs with a 64 bit image.
• Fixed a redraw problem when entering full screen when the grid was showing (and you had "Super scrollable canvas" turned off).
• Fixed a problem where the perspective transform tool wouldn't give a correct preview.

Next up: Acorn 7.4.3 obviously. (And don't worry Retrobatch folks - I've got stuff coming for you as well).

This came up today in response to a support question, and it's a neat trick that I think more folks should know about: In Acorn 7 you can use the Selection ▸ Make Shape from Selection menu item to convert the current selection into a shape, which you can then add a stroke to, or fill, or do whatever you want. You can even add or subtract from the selection using the various keyboard modifiers and make complex shapes from it.

The one exception to this is that it won't work with the bitmap selection tools like magic wand, quick mask, and "Make Selection from Layer". (That'll destroy the fancy math Acorn uses to keep the selection vectors in memory).

Have fun!

A new update to Acorn is out, version 7.4. I've added clone tool improvements, you can now assign a corner radius to bézier curves and star shapes, the color picker now allows you to use float values for the RGB values (so you can get super, super accurate with your colors), and some new command bar actions and AppleScript abilities. There's more as usual, and you can check the full release notes for the details.

While working on Acorn 7.4 I kept on glancing at the version number and wondering why it felt so… familiar and right to me? And then it eventually hit me — I was born in '74. So I really like this version for that reason alone. I think any future big features will be stuffed under the 7.4.x number instead of a 7.5, just so I can keep the '74 around longer. I mean, why not? It's my app and I can do that.

Inflation has been getting me down lately, and I know it has for a lot of other folks as well. So, after a quick staff meeting* and unanimous vote, it has been decided to shave $10 USD off Acorn and Retrobatch's price for a little while. That's like, 25% off for Acorn!

How long will this sale go on? I'm not sure yet, but I'll be sure to call another hands on meeting should any more important decisions need to be made.

* Flying Meat is still just me, with a little help from Kirstin now and again.

We're rolling our 20th Anniversary sale* into a back to school sale. So while it's not as steep a discount as before, you can still pick up our apps at a low price for a while.

But this time around we've brought bundling back. So you can purchase multiple copies of Acorn with a bigger discount, or mix and match by buying Acorn + Retrobatch, and save even more money on both apps.

* Someone failed to write about Flying Meat's 20th Anniversary on the actual Flying Meat web site. This is a criminal act, and the offender has been sacked.

I've started working on Acorn 7.3, and for some reason I got the itch to add a custom convolution filter to it. I've been thinking about adding one for years, and have had some requests for it as well, but it's a bit advanced and maybe not that necessary? But I really wanted it for some reason and it's not a UI change - it's just a filter that's going to be hiding out among the others so you'll never see it unless you want to.

If you want to play along you can do so by grabbing the 7.3 beta from Acorn's latest builds page. The filter is named "Custom Filter" (because that's what Photoshop named its equivalent, and I'm not going to go around renaming stuff just because) and you can find it under the Filter ▸ Misc menu.

The above image is what it looks like when you first add the filter (and you can click on it to view it larger). You'll see a 5 x 5 grid of numbers, with a 1 smack dab in the middle. This is known as the "identity" convolution, which does nothing but let the pixels through unmodified. By the way, I found this painting of a whimsical deer in a short tunnel while recently camping at Larrabee State Park.

Next up I've changed the numbers in the convolution matrix a bit, and all of a sudden the image gets sharper (more noticeable in the larger version). You can also create little blurs by altering the kernel as well (and Acorn comes with some presets for this if you want to play with it).

You can also use convolution kernels for detecting edges.

As well as embossing and making sobel filters.

You can also get a little creative with it by plugging in numbers to see what happens.

Wikipedia has a page on image kernels which goes into detail about what's really going on, and a Google search yields lots more information as well.

The bias field can be used to add to each cell, and the scale value will divide everything by the amount input. For instance, if you're going to apply a 5 x 5 Gaussian blur to this, you'll want to divide everything by 273 (at least with the preset I've added). As long as everything adds up between 0 and 1, you'll be good.

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.

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: http://flyingmeat.com/download/latest/Acorn6Preview.zip
Retrobatch 1.4.4 beta: http://flyingmeat.com/download/latest/Retrobatch1Preview.zip

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.

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.