I’ve always guessed that brush stroke in Aperture 3 create masks, but never looked to see how it might have been implemented under the covers. Then I read this wonderful blog post by John Purlia that explained all. So… a mask is nothing more than a TIFF. I bet any TIFF in black and white can be used as a mask. There’s only one way to find out. Time to play.
The plan is to create a TIFF file from some image that has some texture and then use that as a mask for a curves adjustment. I’ll use the technique described in John’s blog entry to use my texture mask. Finally I’ll save the adjustment as a preset that can be applied to other images. Time to get started.
Starting Image
Results
Adjustments
I shot an image of leaves on a wooden bridge deck several years ago. It lives in my Aperture library. It’s not the best image in the world but I think it will be suitable for use in this test. I created a new version from the master, rotated it 180º, and applied a bunch of adjustments.
The thumbnail images show the start and the post adjustment result. I went for mostly black (masked area) with whites showing up the texture. For this test I though a soft edge on the texture might be better than hard edges so brushed some blur over the entire image then dialed the intensity down a touch. Once I was happy with the result I exported the file to my desktop as an original sized 8 bit tiff.
Note: When picking an image to work with it’d be best to use one that matches the highest resolution you shoot. My test image happened to be from an 8 megapixel 350D. Applying the resulting mask to an image shot with an 18 megapixel 7D results in the mask centered in the image.
create a mask
Now that I’ve got something that I think will make a suitable mask I need to apply it to an image. I picked an image that isn’t very good to play with on purpose. I’ve plenty images in that category to choose from. I checked the curved brick and selected “Brush Curves in” from the gear pull down. In the brush HUD I checked Color Overlay from the gear menu and drew a target. That is the mask I will look for inside of Aperture.
I quit aperture and opened a finder window. A right/ctl click on the aperture library let me select Show Package Contents. That put me inside of the library.
find mask
correct mask
I searched “Aperture Library” looking for a Created date within last 1 days. I then clicked on the “Last Opened” column to order the search results. The first TIFF image was probably my mask. Selecting that item and hitting the space bar showed me the target I’d painted on the image.
That’s the file I want to replace. A right/ctl-click on the tiff gives me the option to “Open Enclosing Folder”.
Open Enclosing Folder
With the enclosing folder open I copied the name of the appropriate TIFF file. Warning: there may be many TIFF files in the folder. Make sure you are playing with the appropriate file or you will clobber previous work to some other image.
I renamed the TIFF texture mask that I created on my desktop the same name as the mask in the Aperture Library. After checking that the names were identical I dragged the TIFF texture mask into the open folder and said it was OK to replace the existing file. I closed the various finder windows and restarted Aperture.
adjust texture
result
How about that. When I adjuste the luminance, red, green, and blue I see the texture from the mask I created. It doesn’t do anything for this particular image, but that is besides the point. It works. I still have lots of questions and will need to play quite a bit more before I hope to understand everything that is going on. That is for later. Now I’ve got the basics.
Save as preset
My final step is to save the adjustment as a preset and make sure that it can be applied to other images. Yep. That’s how I found out that applying the preset to an image with a larger resolution will center the mask in the image.
Enhancements I can think of are using multiple curve adjustments with the same mask and adding additional masks. I also want to see what differences occur to an image when the throw-away mask is set for different brush ranges. There are also grey scales to play with. This time I used a mostly black/white mask with some blur. I think I’m going to be busy.
I hope this information is of use. A few cautions… don’t play with the insides of the Aperture Library unless you feel comfortable doing so and even if you do feel comfortable HAVE A BACKUP.