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What Is Masking  
User currently offlineScreener2 From , joined Dec 1969, posts, RR:
Posted (13 years 4 months 3 weeks 1 day 9 hours ago) and read 1423 times:

Sometimes while screening shots, we will add a personal comment about what needs to be done with the picture to improve it. Sometimes however the user is not too familiar with some of the tools, and we get mail back asking, "what did you mean about...".

So instead of keeping it to e-mail, I thought we'd try to share some of these questions and responses to benefit others as well.

Every few days, I get a request to describe what I mean by "masking". I'll say this particularly when a picture needs selective sharpening.

The term "masking" comes from "masking tape", that paper-type adhesive tape which you can use to cover (or mask) things that you don't want to get paint on, like the door handle when you are painting the door. Masking in a photo-editing program works the same way, allowing you to select parts of a picture to which you will do some processing, like sharpening, and conversely which parts will be "masked", or protected from any changes.

This comes very useful is certain situations. For example:

Click for large version
Click here for full size photo!

Photo © Colin K. Work

On this plane, there are thin stripes close together along the fuselage. If the picture was blurry, and sharpening is applied to the entire plane, stripes such as these quickly start to look like hell, and ends up in a guaranteed rejection. Similar things happen when you see thin daylight between the flaps, or simply on the edges of an airplane, like the wing's leading edge.

Masking allows you to cover up these lines and apply sharpening to the entire picture except the lines. I consider masking to be a key tool needed to make your pictures look the best they can.

The same logic can be used in order to adjust the plane without touching the sky, or vice versa.

I am not familiar with many different softwares, and maybe other people can jump in to describe others. I use Corel Photopaint 8.0, which is roughly the equivalent to Photoshop.

Assuming that similar tools exist in other programs, you will have several masking tools.

Firstly, you will have a positive or negative mask. A positive mask means that the area you select WILL be affected by subsequent processing. A negative mask means that the selected area will be protected from subsequent processing.

Secondly, you have the different masking tools. The most common and easily understandable tool is the rectangular masking tool, where you click on one place in the picture, drag the mouse somewhere else, release the button and end up with a rectangular area surrounded by a wavy border. In Photopaint, by default, this will be a positive mask, meaning that whatever you do after this (sharpening, lightening, whatever) will only be applied to what is inside the rectangle. If you had pushed the selector to make it a negative mask before defining the shape, processing would only be performed on the area outside the rectangle.

There are other masking tools other than the rectangle tool. The 2 I find most useful are the paintbrush and the "Magic Wand". The Paintbrush is easy - you select the tool, select the size/shape of the brush, and run the brush over the area you want to apply the mask to. This is what I would do to the picture above to mask the thin lines so that I could apply sharpening to the rest of the picture.

The Wand is also interesting. Let's say you have a picture like this:

Click for large version
Click here for full size photo!

Photo © Frank Schaefer

If the plane was blurry, and the sky looks like it will get grainy if you apply sharpening to it, you can use the Wand to make a negative mask over the sky, leaving the plane available for sharpening and leaving the sky alone. In Photopaint, I would select the negative mask selector, select the Wand, and click somewhere in the sky. The program will select all the areas of the picture which are of the same color as the point you clicked on (you can define how tolerant the Wand is of slight variations in color). After maybe 2 or 3 clicks around the sky, the entire sky should be masked, and you can go one with sharpening the plane without causing the sky to go grainy.

Lastly, an interesting tool is called "Mask Feathering" (at least that's the name in Photopaint). This allows you to create a fuzzy border around the mask, so that the processing you do in one area does not cause an overly abrupt transition border between the masked and unmasked areas.

This is meant to be just a brief primer to masking. I highly recommend those who are not familiar with these tools to read their program manuals and learn how to use them (especially if you have been getting a lot of rejections).

If there are any other recurring issues like this, which the screeners see, we can do another post. As far as masking is concerned, and questions on this can be posted below.


5 replies: All unread, jump to last
User currently offlineCkw From UK - England, joined Aug 2010, 768 posts, RR: 16
Reply 1, posted (13 years 4 months 3 weeks 1 day 7 hours ago) and read 1351 times:

S2 - a good overview of masking. I'd just like to add one more trick, which is to use masking to improve your skies, particularly if they're a bit washed out.

1 - Use the magic wand tool to select the all the sky - if there is a big difference between the tone values of the sky & aircraft, you can often do this with just one click.

2 - invert the mask so that the aircraft (and ground) is covered, and the sky unmasked.

3 - "feather" the mask a little (3-5 pixels is about right)

4 - now use your software's tone curve and/or level equalization feature to adjust the contrast and tones in the sky - the object is to increase contrast, and possibly darken slightly. Don't use "lighten" or "contrast" functions as these result in a crude, unnatural effect.

Cheating? Well, perhaps just a little, but no more so than using a grad filter, or burning in the sky in a darkroom.



Colin K. Work, Pixstel
User currently offlineSotomayor From United States of America, joined Jun 2005, 0 posts, RR: 0
Reply 2, posted (13 years 4 months 3 weeks 1 day 5 hours ago) and read 1331 times:

Using the magic wand tool to select the sky (positive mask) you can apply a filter like Smart Blur (in PhotoShop) to reduce the overall grainy appearance of the picture, without blurring the rest of the picture (e.g., aircraft). This can improve the picture dramatically because the sky (especially without any cloud covers) is usually the part where most of the grain is quite visible.

Tweaking the magic wand tool is required to make adequate selections. Now that I have a film scanner, these are techniques that I'm becoming more proficient at, since film scanning reveals so many details of the picture that the print scan was hiding.

Here's an example where I applied the Smart Blur only to the water surfaces:

Click for large version
Click here for full size photo!

Photo © Orlando Sotomayor

This is a picture I just recently re-uploaded with a much better scan.

User currently offlineBO__einG From Canada, joined Apr 2000, 2771 posts, RR: 18
Reply 3, posted (13 years 4 months 3 weeks 1 day 3 hours ago) and read 1324 times:

Very InsightfuL!  Big thumbs up

It looks like I have a clear idea of it now brought up to a further level ..

It seems like I have been doing some of that for my pictures..Without knowing what it is..@!
POsitive masking is what I would be doing as at times I would just put box around the registration or the airline logo/titles or even the landing gears to touch things up.
But with the magic wand and the Lasso tool for photoshop.. I think I can bring some of my pictures up.

Im one of those photographers whos trying to get soem more accepted..

Thanks S2..


Chance favors the prepared mind.
User currently offlineMirage From Portugal, joined May 1999, 3125 posts, RR: 14
Reply 4, posted (13 years 4 months 3 weeks 21 hours ago) and read 1304 times:

I've no comments but read it very careful, thanks for your time to wrote that explanation.


User currently offlineMightyFalcon From Oman, joined Jun 2001, 384 posts, RR: 9
Reply 5, posted (13 years 4 months 3 weeks 8 hours ago) and read 1270 times:

Many thanks, Screener2 and to the others who added some comments.

A bit of technique is greatly appreciated by beginners like me.

Feel free to write some more, anytime.


The sky has no limit...
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