Simulating Depth in Paint or Graphics

[Synthetik]

When you look at a raised textured surface or at objects in the real world that are lighted, you perceive them as having depth. A raised textured surface could be things like a canvas with thick paint, or pieces of wood pasted on a board, or a pile of pebbles. Now let's assume that the lighting is coming from the right side of the object of interest for discussion purposes. If you think about it, since the light is coming from the right side and because the object or surface is raised, the light will be generating shadows on the left side of any raised parts of the textured surface or on the left sides of the object. Now when your eyes look at the lighted surface or object, your brain is analyzing many different aspects of the image coming into the brain, things like color and shape and texture and also shadows. Because you have lived in the world for many years and because in the real world lighted objects with depth have shadows, the visual centers of your brain are able to analyze the visual clues that these shadows in an image provide and when you look at an image that has appropriately placed shadows you see the perception of depth. This is true whether the image is what you are looking at in the real world, a photo you took of something in the real world, or a totally artificial artistic image you created. So if you want your artistic image or painting to look like it has depth or raised textured surfaces when viewed, these visual shadow cues of depth need to be in the image you are creating. There are other aspects of depth perception but for the sake of this discussion we are just going to focus on lighting cues for depth perception. For example things like the spatial frequency of textures and the saturation of color change with changes in apparent depth in images, but we're ignoring those effects for now. And if you are looking at a textured surface they would not be very noticeable anyway, not like if you were looking off at things a great distance away. So if you are creating an artistic image on the computer then you might expect that one way to add a perception of depth to your painting or artistic image is to add some of these shadow cues that are created by lighting effects. And what we are really talking about is adding a lightness change on one side of any areas where you want a viewer to perceive a discontinuity of depth. So how do you go about doing this? You could paint all the edge shadows in by hand. But that could get kind of tedious. Another approach is to use paint presets where the shadow cues associated with the paint itself is built in. Another approach is to use some kind of image processing operation after you are done painting to generate the shadow depth cues. A good place to start if you want to use prebuilt paint presets that have lighting effects built in is to look for preset categories with the term 'lighting'; or 'gradient' in the title. So categories like 'Default-3D Lighting' or '3.5 Collection-Gradient MultiNibs' for example. When you paint individual strokes with these presets the paint strokes themselves look raised or globby or like rough lighted textured paint. Of course you can always dip in the paint synthesizer editing panels if you are curious as to how these presets that create lighting depth effects directly in the paint are constructed. Many of these presets incorporate effects generated from the 'Brush Load' control panel. You can see if this is the case by going to the Paint Fill Setup control panel and looking if either the Fill From or Mod Type popups are using a setting that has the phrase Brush Load in it. There are different types of Brush Load effects, they are Lighting Effects, Image Processing, Gradient Generator, and MSG. All of these different types are capable of creating a different kind of raised look with the appropriate settings. What 'brush load' means is that a small image the size of the brush is being dynamically created in real time as you paint. Every time the pen moves a new image is created, which you can think of as being a simulation of a dab of paint on a brush that is then applied to the canvas. So if the artificial dab of paint has depth cues drawn into it that simulate the kind of shadows you would see if it was a real dab of raised paint, then your brain will perceive it as having depth when you look at a painting created with it. If you are technically inclined, then there is a tutorial on video tutorial disc #3 that explains all the controls in the Brush Load control panel in great depth. If you are not technically inclined, then your head may already be spinning. So for you, the take home message is that if you have a particular paint preset that you would like to give a more raised look, then setting the Paint Fill Setup control panels Fill From popup to the Brush Load setting is a good place to start. You could then goto the brush Load control panel and choose a Lighting Effect or Gradient Generator type, both of which are good starting points for creating paint with a raised look. Or as i said, if any paint synth editing is too technical for you then you can just look for preset categories with 'Lighting' or 'Gradient' in the name and see if any of those presets are what you are looking for. This kind of high level paint preset edit is a good example of what is provided in the paint synthesizer macro edit menus, so we'll add 'give this preset a raised look' to the list of possible macro edits to add to future versions of Studio Artist. Suppose your painting is already finished and you did not use a paint preset that has a lighted or raised appearance to create it. Or suppose you are working with the Vectorizer and you have a canvas composed of flat solid color regions. You can add depth after the fact by using some form of image processing that adds the shadow depth cues we discussed above to your painting or vectorized image. The Gradient Lighting Image Operation is probably the first place to go to if you want to add lighting effects to an image. A little bit of this processing can go a long way, so i usually turn the Mix parameter down from a full 100% replace to something smaller when i use the Gradient Lighting operation. there is a tutorial that discusses the use of gradient lighting ip op for adding depth to vectorized images here. There are other 'post-processing' approaches to creating a lighted look besides the Gradient Lighting Ip Op. Displacement mapping with an edge composite would be one. Directional blur with an appropriate compositing option would be another. you could use layers to do this, or the built in compositing in the studio artist image operations. And of course there is the Gradient Ip Op. So, i hope this little discussion provides a little insight into what to do to help create a raised or lighted look in a painting or an artistic image you are creating. i tried to write this to address non technical as well as technical readers. if it's still too technical let me know, or i'm happy to explain anything in more detail if you have questions.

[Dee Flouton]

Thank you for your in-depth explanations here and in another thread. There is a lot to digest and attempt to implement. Following up on these processes will be a challenging, but hopefully rewarding experience!

[Charles Floading]

I've also gotten pleasing faux 3D lighting results using the Smart Morpholize IP Op.
Set the Agorithm to Expand 2
Effect Canvas Composite to Edge 2
And Mix to about 50%

It's a subtle effect, but like most effects, less is more.

Something of a philosophical or theoretical aspect of lighting that I like to think about is how much of the lighting effects you can attribute to the image itself.

When I paint something using natural media, say oil on canvas, the raised texture of the brush strokes will appear differently depending on how I light it once it's hanging on the wall. Someone looking at this painting will have a slightly different experience of the lighting depending on where they are standing, what time of day it is, and even if they are wearing an all white shirt vs an all black one (light bounces off their shirt, then off the painting, then to their eye.)

Since a digital image never interacts with display lighting, I have to decide how much "fake" lighting I want to add. And this lighting might compete with the content of the image! My digital painting or my processed video image will have it's own light sources. I can really muck things up if I try to add the illusion of a textured surface or raised paint strokes to an image that has striking lighting (think silouettes, backlighting, or subjects that are lit from beneath.)

Maybe there's someone with an art history degree in this group who can recount some of the history of the use of brush stroke as a part of the art. I know that this was/is something that was/is debated.

[craig deeley]

I have been a little obsessed with this 3D depth in a Preset "brush" for years when working with SA.
I am of two minds about it.
One: I want an effective immitation of a loaded oil paint brush. I just do.
Two: I am not satisfied with what I get when I play with SA (or any application) trying to fake depth and find as often as not I prefer just a more or less non "bumped" look as any fake 3D look.

Nevertheless - I do still try to come up with a loaded ol brush effect now and then.

I did experiment with this look a short while ago looking for something - and ended up with a few "ok" looking brushes that I could use to fatten up my Preset folder.

3d_oil_CD_0108.zip are four Presets doing some oiliness.

These use the canvas a lot and have some odd color starts on them... They are like the start of a conversation for me. Some place to jump off from.

Let me know if they lead anywhere for you SA folks out there.

: )

Craig

3d_oil_CD_0108.zip

[mark g]

very nice Craig, I look forward to playing more with them in my work !

[craig deeley]

I have been experimenting with coloring book illustrations with a more natural or traditional media like look using SA. I am looking for several things.
• The process needs to be hand drawn using SA. Be hand drawn and look (mostly) hand drawn.
• The process needs to have a look that is not too digital (pixels, patterns etc that make the effect look machine made)
• The process has to be as easy as possible in terms of minimal steps to create the art... and easy in terms of performance on the machines I am using (old G4 and new Mac Mini - not the highest end)
• The Presets need to be quick to load and or alter on the fly with adjustments in the Paint Synthisizer.

These Presets simulate a VERY thinned oil wash aplied with a bristle brush on a moderately bumpy canvas surface. They are at a size that works well on a image with dimensions of 1000x1000 pixels at 150 DPI.
The Presets use white as a source to define the bristle/brush stroke effect.

I added an image to my gallery (oiltest) that was colored with these... tho the Presets effects are only visible in the detail (comp_detail) - I am hoping that this look would translate well to print when bumbed up in DPI and contrast.

If anyone finds them useful - I would love to hear about it.

Craig

cd_oil_backtexture.zip

[Donna Kuhn]

thank you, craig

i really enjoyed the last ones you posted.

donna

[Dee Flouton]

Thanks, Craig I will try them out as well. I have the same set up as you do.
Dee