Review: Acorn, Intermediate Image Editing for the Mac

What is Acorn?

Acorn is a basic image editing application for the Mac from Its standard price is $49.99US, but it is specially priced at $29.99 US during the month of May 2013. It can be purchased from the developer, or from the Mac App store; with all the usual advantages and disadvantages of each method.

Where’s the Market for Acorn?

Acorn uses the tag-line: The Image Editor for Humans. While that line casts me on the role of non-human, I understand perfectly what it means. Apple owns the low-end of this category with iPhoto, for organizing images, and doing simple, mostly global, corrections to them. And Adobe owns the high-end with Photoshop and Lightroom. In fact, the only Mac application that comes to mind in between these two extremes is Adobe’s Photoshop Elements, which is a stripped down version of Photoshop for non-power users. Acorn certainly fits in the same zone as Elements, without the name recognition that Photoshop offers, or the value of having the app you’ve been learning be an exact subset of the app you may end up graduating to, as is the case with Elements and Photoshop.

How’s the Interface?

Since virtually all non-Apple, non-Adobe image editors are on Windows, or from Windows, it is typical to expect a rather unattractive look and interface in such programs. Acorn, refreshingly, looks like a well-designed Mac app. With its most recent update Acorn uses much the same general layout as Elements or Photoshop, with a double-row vertical tool palette on the left edge of the screen, and further tool control windows to the right of your image. While it is not an actual subset of Photoshop, a Photoshop user has no difficulty navigating the app, and learning in Acorn would not leave a new user at a big disadvantage in moving to Photoshop later.

Acorn Interface

Acorn Interface

What’s the Feature Set?

If you are not the type of user that feels a need to work in Lab space, convert images to CMYK, or perform other power functions, Acorn might well fit your more-advanced-than-iPhoto needs. It offers many of the typical basic and intermediate functions, including layers, masks, and even alpha channels; as well as most common selection, cropping and adjustment functions. One interface element that takes a moment to get used to is that many of the tools found in the Image column of Photoshop’s menu bar are under Filters in Acorn. We’re used to looking under Filters for Blur, Sharpen, and Stylize effects; in Acorn you’ll find Color Controls, Exposure, Gamma, Grayscale, and other such items there as well.

Screen Shot 2013-05-03 at 1.46.04 PM

What about HighBit Files, and Other Formats?

Acorn has no trouble opening images saved at 16 bits per channel, or saved as Tiffs with common Tiff compression formats. Pings are also supported. Even layered Photoshop (.psd) files. So most formats the typical user will come across are covered.

Does It Deal with RAW?

Acorn is capable of opening RAW files in at least some formats. Its RAW converter is simple, and best used for emergency situations where a RAW image needs to be viewed, or a quick Jpeg created from it, and a full fledged RAW editor is not convenient or available. The controls in Acorn are not powerful enough to be effective in adjusting RAW images using the SpyderCube. HSL controls for use with SpyderCheckr are also lacking. So consider Acorn not as a RAW converter, but a RAW converter substitute.

Acorn RAW Import Dialog

Acorn RAW Import Dialog

How’s the Color Management?

This question is of special interest to Datacolor customers. Color presents identically on-screen in Acorn and in recent versions of Photoshop. sRGB and ProPhotoRGB versions of the same image present identically in Acorn as well. So clearly the application is utilizing the display profile; and converting from the tagged image space to the display profile correctly.

Acorn Image over Photoshop Version

Acorn Image over Photoshop Version

The printing dialog from Acorn presents are the standard versions accessed other applications for the same graphics printer, allowing a custom printer profile to be selected. Printing sRGB and ProPhotoRGB versions of the same image gives matching results; so printer color management seems to be functioning correctly as well.

Acorn even has an Assign Color Profile command. There is no matching Convert to Color Profile command, so this limits users from converting the pixels in an image from one color space to another (such as the conversion from sRGB to ProPhoto used for the tests above), and allows only the more practical task of setting the correct color space for an image which is either mistagged, or more likely untagged. Assigning sRGB to the ProPhoto version of the test images used for this article instantly changed the colors to be incorrect, as would be expected, and reassigning ProPhoto instantly corrected them again.

Acorn's Assign Color Profile option

Acorn’s Assign Color Profile option

So What’s the Conclusion?

More and more photographers are going without a copy of Photoshop, given its price tag of several hundred dollars. Many of these users are using the much more affordable, and for most photo tasks much more practical, Lightroom to organize and edit their images. There are also the users still working in iPhoto, but who have reached the point of wanting more advanced features than iPhoto offers.

Such users have the need to occasionally make localized edits, layered files, composited images, images with text added, and other such tasks not covered by Lightroom or iPhoto. Acorn is a very legitimate option for both these cases. It can even be set as the optional second editor from Lightroom, to open Lightroom exported files directly into Acorn for pixel editing.

With Photoshop Elements listing at $99US, and even on special tending to run well above Acorn’s price, Acorn is certainly an easy-editor worth considering.

Credits: C. David Tobie, Copyright 2012. Website: Return to Blog’s Main Page

Behind the Scenes: How This Image was Captured and Processed

Final Image, with 100% Scale Detail Inset

Final Image, with 100% Scale Detail Inset (Click for 100% View)

At 6AM this morning, the marine fog layer was thicker than usual in the California Central Coast. There was a diffused glow hinting at a sunrise to come, or that might never come, given the fog layer. So the tripod and camera at hand were grabbed immediately, as sunrise shots can fade quickly. This was shot using a Canon 5D Mark lll, with the L-series 24-105 f:4 lens.

Stepping out onto the balcony, the palmetto tree in the image was the best choice of foreground subjects, so the camera was set up to capture that, plus the sky to one side of it. A five second exposure at f:4 and ISO 200 seemed to offer a good balance, but five seconds was long enough to let the lightest of breezes blur all the palm frond tips. The camera was set to “two squeeze mode” where pressing the shutter the first time raises the mirror, eliminating mirror shake in the actual exposure, and the shot does not occur until the second time the shutter is squeezed. A remote trigger tool would have been appropriate, but there was not one available, so a light touch was used, along with many exposures. The multiple exposures were also shot in an attempt to catch a frame between breaths of wind. Of all the frames taken, there was one where nearly all the tips were still.

The sunrise gradient is from rather unusual lighting circumstances. The lights from the town are below where this shot was taken. The gradient is caused by the sunrise colors diffused through the fog above, with the town lights glowing below, and adding a yellow tint. There is no “sky” involved anywhere, its all gradated colored mist. To the naked eye, the scene was a black silhouetted palmetto with no detail, against a dim tinted mist.

The capture was processed in Lightroom 4, which offers significantly improved functionality for adjusting dynamic range in the various elements of an image over earlier versions. The global saturation was increased considerably, but the hues were not changed, and no type of artificial gradient was applied to the image.

This shot was a challenge for the 24-105 lens on a full frame sensor, given the very diffuse, even light field involved, which made the darkening at the corners of the frame very apparent. Even after applying Lightroom’s lens corrections for the lens, and increasing the vignette removal amount, it was still necessary to clone the very corners, just slightly, to keep them from being dark. It required very subtle work, with reduced opacity, heavy feathering, and just a tiny move, to keep from showing further out. Corner correction was the only localized adjustment performed; all other adjustments were global LR4 corrections.

Credits: C. David Tobie, Copyright 2012.   Website:   Return to Blog’s Main Page

Tutorial: Editing Fall Foliage Photos

At the peak of fall foliage season the colors can reach fluorescent levels, by borrowing light from outside the visible spectrum and reemitting it in the red through yellow zones. Because of this, foliage photography requires careful editing to produce the type of image our eye recalls seeing. All too often people make the wrong adjustments, resulting in images that look false and unsatisfying. Lets look at a set of foliage photo adjustments, first by the numbers, and then tweaked to emulate the eye’s response, to see where photographers usually go wrong.

The Starting Point

Typically the camera is left to determine the best whitepoint, and to adjust at least one of the exposure parameters. The success of this varies with the subject matter, but often the result is not accurate, and the look is not ideal. In the image below, the default settings, when opened in Adobe Lightroom 4, produce a flat image, with insufficient color. Keep in mind that no color adjustment should be done to images without first calibrating your display.

Image at Defaults in Lightroom 4

Other elements in a fall foliage image still need to be correctly exposed and white balanced, for instance the twigs in this macro can’t be too red or too saturated, or the overall believability of the image will be lost. The best starting point for correcting camera settings for any image is with the SpyderCube. For this image the adjustments from shooting the SpyderCube in another frame earlier in the series are applied to the image. The camera default settings in Lightroom are shown next to the Cube-adjusted settings in the image below.

Default Settings, on left, and SpyderCube Adjustments, right

These settings increase the dynamic range of the image, making the midtones more dense, the shadows and blacks darker, adding punch to the image. Too often the assumption is that lightening fall foliage will make it “brighter” when the actual result is to make the colors weaker as they get lighter. Often, careful deepening of the midtones actually intensifies the foliage colors, as well as increasing the punch of the image as a whole. Note that the whitepoint of this image was fairly well estimated by the camera, so the color change caused by whitepoint correction, which can sometimes be quite significant, is minor in this case. The image below shows the result of applying these adjustments to the same photo.

Image with SpyderCube Adjustments applied

Camera Color Correction

Before making any visual adjustments to the image color, it is best to make global color corrections for the camera used. In this case I now applied a SpyderCheckr color calibration for this camera. The change to the image is subtle, and actually reduces the color saturation of the red channel, which is technically correct; but not necessarily in line with the artistic intent we have in mind for this image. Here is the SpyderCheckr adjusted version of the image below.

Image with SpyderCheckr Adjustments applied

Artistic Intent

Now that the dynamic range, white balance, and camera color have been corrected, I can make further adjustments to bring out the fluorescent nature of fall foliage in the image, while feeling comfortable that the overall corrections of the image will be in-line with the other images from the shoot that will be used in the same series. The lazy solution for fall foliage correction is to simply increase the global image saturation with the Saturation slider. However, many fall foliage images include greens and other colors, which will have their saturation increased along with the foliage colors, resulting in an image that the eye immediately sees as false.

The preferred solution is to adjust the saturation of the foliage color channels, while keeping an eye on the realism of the resulting image, and watching out for possible posterization in color transition zones. The image below shows a closeup of what happens to out of focus areas with color transitions when the changes between adjacent channels are excessive, and gradients posterize. The version at the bottom shows the final choices, which minimize this posterization. Note the reduction in banding around the green area.

Image with excessive adjustments between adjacent channels, top, and reductions to improve gradients, below

The next consideration is out-of-gamut colors. Its easy, when attempting to create the type of fluorescent results fall foliage can produce, to exceed the gamut of both your display and your printer. Gamut warning tools can be helpful in avoiding this situation, but the eye is the final arbiter. If further increase in the saturation of a color does not actually increase its saturation, and perhaps causes other side effects instead, then you are working outside the gamut of your display. Reduce the saturation increase you are producing until you can distinguish saturation changes with each slider adjustment.

Below are the SpyderCheckr HSL adjustments on the left, with the tweaked saturation settings on the right. These tweaked adjustments are only to the saturation sliders, and only for the red, orange, and yellow channels, where fall foliage colors occur, plus adjustment to the green channel to smooth color transitions. Avoid excessive green increases to keep the image believable. If your foliage was shot at a long distance, especially through humid air, then global increases to saturation, contrast, and sharpness may be needed to compensate for atmospheric perspective effects.

SpyderCheckr Adjustments, on left, added Visual Adjustments, right


Below is the resulting image. It has been converted to sRGB for the web, so not all colors desired for inkjet output can be included in the images shown here. But the general result of correcting dynamic range, whitepoint, camera color, and foliage fluorescence, instead of simply increasing the saturation slider show even in the sRGB version of the image. In order to print this image, I would now move on to using Lightroom 4’s softproof function, to work with the capabilities of my printer, ink, and media combination as described by my SpyderPrint output profile for the combination.

Image with Visual Tweaks to R,O,Y, G Saturation Sliders

Credits: C. David Tobie, Copyright 2012. Website: Return to Blog’s Main Page

Back By Special Request; More Tuscan Images

The response (mostly direct, but some on Facebook or WordPress) to yesterday’s sample of my “Through a Lens Darkly” images was gratifying; thank you all. I have processed several more today, and will add a few below. The link to see the whole collection on my photo website is here: I plan to cover a wide array of image types over time, this is just the first set to be highlighted here. Others are in process, or awaiting processing time. Buon Appetito!

Credits: C. David Tobie, Copyright 2012.   Website:   Return to Blog’s Main Page