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Using the Difference blend mode in Photo-based Art
O.K. I admit it. For over a year I failed repeatedly to find useful uses for the Difference layer blend mode during numerous flails at generating Photo-art.
Out of some sense of misplaced obligation I’d give Difference (as well as Exclusion) a try each time I clicked through the blend mode menu, hoping that "this time" would be different and I would finally get pleasing results. It never happened.
Over time Difference fell into the same category as obnoxious and misunderstood inlaws: While it’s politically correct to be civil towards them in public and acknowlege they might be useful to others, there’s no law forbidding aggressive avoidance.
Although I’d probably read no less than 20 articles, chapters and tutorials on blend modes, when I got to the discussion on Difference my eyes would usually cross and/or I’d go to sleep while trying to absorb how and why I would (or could) ever use Difference. Based on enlightening passages such as the following, can you blame me for getting the nods?
THE DIFFERENCE AND EXCLUSION BLEND MODES
The Difference blend mode subtracts a layer's colors from the underlying layer to produce a pretty dramatic effect. The Exclusion blend mode produces similar effects but to a lesser degree.
The Light Finally Comes On - Sort Of
The other day an image created in this thread by our site founder and fearless leader, Doug Nelson, helped turn on the lightbulb for me… not from the perspective of finally comprehending how Difference works from a technical and mathematical perspective, but how I might experiment with it differently.
The attachment is another hack of my Mom, bless her heart, against which my “new Difference experiments” were performed. The key layer, I believe, is “B” (blend=Difference), against which I ran the BuzzPro plugin using the watercolor.stk preset. The (inverted) “difference” between the B and the A layers is what gives the image its base unique (and kind of sketchy) character.
I also tried running individual and combinations of filters like Colored Pencil, Angled Strokes, Dry Brush, Fresco, Watercolor, Sumi and the other usual Photoshop arty filter suspects against layer B with varying (and sometimes pleasing) results. Your mileage will very.
A little farther up the stack is another "difference pair" of layers, (E and F), used to further add character.
Lastly I tried using the Move Tool and the arrow keys to “offset” a filtered or textured layer B slightly from layer A, thereby creating additional interesting “differences” between corresponding pixels on each layer.
Trying to add some "color" to this concoction just didn't pan out, so I stuck with unsaturated.
Thank you, Doug, for helping me see the light and find closure to the burning question, “What’s the Difference with Difference?”
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Retouch Pro members . . .
OK. Your turn.
If you have examples of images in which you used the Difference layer blend mode or general comments on circumstances in which you finde the Difference blend useful, please share them. There is no expiration on updating this thead.
Don't feel like example images or pearls of wisdom necessarly need to be Photo-art centric.
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I had a REALLY FUN today. Hope you did too!
Last edited by DannyRaphael; 07-13-2002 at 09:19 PM.
Here's a version using the same steps as the previous post, except that the Colored Pencil filter was used in place of BuzzPro on the "B" layer.
Since my background is boring old prepress production - I find difference mode useful for boring production tasks. <g>
For example, in the RetouchPro 'goodies' section I have uploaded some actions. Two of these actions use difference mode as a key step in the action.
'SmartDuster' is designed to isolate dust onto a separate layer and to filter it away - to save on tedius clone or healing tools on many small specs. Difference mode is used to build the mask which isolates small dust and other fine content (sadly this can include image detail).
'IsolateHealing' is designed to mimic the results of clone stamping to a transparent layer - when using the healing tools to an entire duped layer or larger selections which have been turned into a new layer. Difference mode is used in a similar way as in the SmartDuster action, to create a mask from the difference between the original and healed layers. The mask is then used to isolate the different pixels.
Difference mode is also great for aligning images which share some similar pixel content - black results as a perfect alignment when the same pixels are perfectly aligned. This can be handy when using the multiple scan technique to mimic scanner hardware multisampling to reduce noise.
Difference mode and then the equalize command can exagerate minor differences between two images.
Thanks so much for sharing your insights. Just what this thread needed!
For the curious here are a couple links to further information on uses for the Difference blend mode:
* See how Difference was used for creative effect in this RetouchPro Manipulation Challenge.
* Another RetouchPro member uses Difference in a Retouching Challenge.
* One of our favorite authors, Katrin Eismann, uses the Difference blend mode as a key step in this masking tutorial. (PDF)
* From MyJanee.com, using Difference in conjunction with Gradients.
* Festive Type Effects from ActionF/X guru, Al Ward.
* A tutorial from the Photoshop Guru.
* An excerpt from a Jay Arriach tutorial. Jay's site, overall, is exceptional.
Keep having FUN!
Click here to see my entry in the photoart mini-challenge #5 for what I did with the difference blend mode. I bet if I worked at it I could figure out how to make an image look exactly like I wanted it to by using that blend mode (instead of doing it to see what strange colors it decided to give me like I have done before).
Added link to mini-challenge #5. DannyR.
Last edited by DannyRaphael; 07-15-2002 at 08:09 AM.
Your Mini-challenge #5 entry graphically illustrates how Difference can be used to generate unpredictable and pretty far-out-there coloration (and I mean that in the 'good sense'). The more I play around with Difference, the more possibilities I see for it.
I guess that's the point of this forum... Having fun and experimenting, right?
That image in particular inspired me to take another swipe at the image of my Mom (what a good sport, huh?) to see if I could take Difference in the direction you emphasized, while illustrating its potential to emphasize edges.
The Background layer was first filtered using Mosaic, followed by Tiles. Lots of potential edges now!
The Background Tile / Mosaic layer was duplicated and blend mode set to Difference. Then, after choosing the Move tool, I nudged the top layer down and to the right using the arrow keys. As expected with each click of an arrow key edges became more and more priminent plus there were some very interesting colors!
For even more edge emphasis I applied an oversharping run of Unsharp Mask (Amont=500, Radius=8) on the Background layer. Yikes!
To remove color (temporarily) a Hue/Saturation adjustment layer was added to the top of the stack, Saturation= -100. Then I airbrushed black onto the Hue/Saturation adjustment layer where I wanted colors to reappear.
The Hue/Saturation adjustment layer was duplicated and inverted (IMAGE/ADUST/INVERT) and the Saturation slider moved from -100 to +50. This added some real pop to the colors, while leaving the grayscale portion of the image unchanged. Now we're cooking!
Flattened the image and duplicated the resulting Background layer, changing the blend mode on the Background Copy to (guess what?) Difference.
Using the Move tool and arrow keys again, the top layer was nudged down and to the right, giving further emphasis / dimension to the hard edges.
Can you hear the sitar playing in the background and smell the incense buring? You can? Wow!
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In summary the purpose of this post and attachment was to illustrate some additional possibilities of the Difference blend mode (colors, edge emphasis), which should not be confused with any notion that I think this is a "great" image of my mother.
I welcome critique, questions or comments on the method. If you feel compelled to give feedback on the final image per se ("Gee, Dick. I give it a 65. I liked the song, but it was kinda hard to dance to."), resist and go back to sleep. You missed the point.
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You, too can have FUN by making a Difference and using it (un)wisely!
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