Friday, May 28, 2010

Class Notes - May 26, 2010

  • The first viewing of a painting after a break is gold.  Not taking advantage of it is like someone handing you a $20 and you flush it down the toilet.  The longer the break, the larger the bill you are flushing away.
  • Difference between "light" and "highlight" modeling factors
    • Light - generally facing the light source, does not move on object's surface.
    • Highlight - functions as a reflection and thus follows "angle of incidence = angle of reflection" from way back in physics class (like a mirror).  Highlights will move around on the form as you move your eye position, whereas the light modeling factor will not.
  • Highlights are an indicator of the glossiness of the object's surface material.  
    • Some facts about highlights:
      • When a highlight is very distinct (glossy surface), the light & halftone modeling factors will be slightly darker & slightly more chromatic- though it's easy to overstate how much the color darkens due to simultaneous contrast.
      • As the highlight gets less distinct (matte surface), the light & halftone modeling factors will get slightly lighter, & the chroma will get slightly lower. The hue in the light area will shift towards the color of the light more than the halftone.  In other words, the halftone remains closer to the local hue of the object.
      • Bonus highlight fact: On metallic objects, the highlight will take on the hue of the object's local color, and will remain much higher chroma than a non-metallic object.  On non-metallic objects, the highlight will be the color of the light mixed with some amount of the local color of the object.  The glossier the object, the less of the local color to add.
    • Some facts about glossy versus matte
      • To make an object look wet, give it a strong highlight, lower the value in the light and halftone, and raise the chroma in the light and halftone.  In other words- make it glossy!
      • Wetting an object (in real life) is a useful trick to temporarily clarify an object's local color.
      • Bonus Glossy/Matte fact:  On a matte surface, the highlight disperses across the surface and lightens its value.  This is why glossy paints can achieve darker darks than matte paints.  It's also why glossy printer paper and glossy varnishes give a wider range of values.
  • Pay attention to your mistakes
    • They're usually physical mistakes, and the physical stuff is what you can't learn from books.
    • Don't beat yourself up- see if something cool happened.  If you're sight-reading on the piano or guitar, if you make a mistake you might discover a nice jazz chord you can use later.
    • Watch for happy accidents, but don't be a lazy bum and leave them in if they look good by themselves but detract from your painting.  However, the physical process by which a mistake happened could be the perfect solution for a problem at another time.
  • "Not to make like a housepainter- to touch, to touch!"
    • Don't start smearing that color all over the canvas until you've touched a small bit on the canvas to see if it's right.
  • Paint Mixing
    • Two paints will mix generally in straight lines through color space.  However, in reality they tend to mix along curved lines in color space.
      • Mixing two paints together will always produce a mixture that is darker than the lighter of the two paints.  How much the value lowers depends on the exact pigments used.  In some cases, the mixture can be darker than both paints.
      • Mixing two paints together will always produce a mixture that is lower in chroma than the more chromatic of the two paints.  How much the chroma lowers depends on the exact pigments used.  
        • The further apart the hue of the two initial paints, the lower the resulting chroma.
    • The perceived color of a paint does not dictate how a paint will mix.  Two paints that have the exact same hue, value, and chroma but are made up of different pigments might mix in different ways with a third color.
      • Thus, it's impossible to say that any abstract color (red, blue, etc) has definite mixing complement when dealing with paint.  It is, however, possible for a physical pigment to have a mixing complement that will mix to a neutral gray.  Interestingly, a pigment can have more than one mixing complement, and these mixing complements may be different colors.
  • The effect of the type of light source on the terminator
    • Sunlight (parallel rays)- terminator edge will be sharp and will "bisect" the object.
    • Spotlight - the terminator edge will be slightly less sharp as compared to sunlight (but still sharp), and will be slightly closer to the light source, depending on how close the object is to the light.
    • Diffuse light (north light, cloudy days)-  The terminator edge will soften, and move away from the light.  The larger the light source (i.e. a window or the sky), the softer the edge of the terminator and the further away from the light.
  • Modeling factors on basic forms
  • Blogs
    • Gurney Journey, Nathan Fowkes, and another guy that Renee mentioned.
    • Blog exhange?
  • The halftone happens later than we generally think.
    • While the exact line between halftone and light is somewhat arbitrary there's a tendency to make the division between halftone and light about halfway "around the form", where the form would be turned about 45 degrees away the light source (this is known as its "inclination to the light"). 
    • In fact, the falloff of light happens much more slowly. Check out this chart from the excellent site  Notice that when the inclination of the surface is 50 degrees to the light, the brightness is still at 82%!
    • There are two caveats here, though.  The first is that brightness is not exactly the same as value in paint, and that this chart assumes a glossy object and ignores the highlight.  The percentages would be different for a matte object.  Nonetheless, the important point is that the value drops in a way that is much different than we think.

Tuesday, May 25, 2010

Edge Contrast

One of your primary tasks when painting realistically from life is make decisions.  If you're confused about what you see or what you're doing, what goes onto your canvas will likely be confusing to the viewer.  There are all sorts of decisions we need to make in a painting, but there are some easy places to look for information to help you out.

One of those places is along the edges of every form.  This is a great place to judge contrasts in value and color- one side of each edge will be lighter, and one will be darker.  Occasionally they will be the same value, and only very occasionally will both sides of an edge be the same color.  Really paying attention to these relationships around each form and clarifying them in the painting can solidify your forms without a lot of effort. Of particular interest is where the relationship switches- as you trace along the contour of one form, the inside edge might be darker than the outside edge, but then at a certain point (often as the form is leaving shadow) the inside form will be lighter and the outside darker.

For some reason these judgments are very easy to make along contours.  Say we have two swatches of similar, but not the same, color.  If someone held the two swatches up a couple feet apart, it would be difficult to tell the difference between them.  But, if we saw one swatch right next to each other or partially overlapping, the difference would be very easy to see.  This is useful to take advantage of while painting.

Edge contrast is different from- but related to- edge quality.  Edge contrast refers to the difference in color on either side of a contour, and edge quality refers to the softness or hardness of the edge between the two colors.

Saturday, May 15, 2010

Local versus Perceived Color

Local Color

Local color refers to the actual, physical color of a surface independent from the effects of light and shadow.  Local color is the answer you give when someone asks you "What color is it?".  For example, if you had to fix a hole in a wall, you spackle up the hole and then paint over the repaired area with paint that matches the local color of the wall. If I asked you what color your shirt is, you would respond with its local color.  This color wouldn't change regardless of the lighting situation- even in the dark you would still say the same color.

Perceived Colors

Though it is almost always extremely helpful to know the local color of an object you are painting, often you will not actually mix the local color and use it in your painting.  This is because the effects of light and shadow create many variations of this local color, which we will call Perceived Colors.  This is what actually reaches your eye in the form of rays of light- not the local color.  However, the human brain seems to be geared towards processing the perceived colors and determining the local color of an object.  If you see a green apple, you understand it as a green apple, not a dark green, medium green, and light green apple.  Most children begin coloring by using the local color to fill the entire area of an object.  It's only later that we become aware of "shading".

Perceived colors includes the shading created by light, along with other effects such as the color of the light, the texture and material of the object, it's position relative to the light, and many more.  Perceived colors can vary greatly with a change in any of these factors.  Note that colored lighting especially can dramatically alter the perceived color.

A computer graphics scene of colored objects.

The local colors of the objects in the box,
ignoring light & shadow

The perceived colors under white light, yellowish light,
bluish light, and very red light (clockwise from top left).

In the examples above, notice that the local colors of the objects rarely, if ever, appear in any of the lit scenes- particularly when the light source is colored.

What Does This Mean For the Painter?

If we want to paint realistically, we need to paint colors that mimic the perceived colors.  If we put them down skillfully, they will cause the viewer to understand the objects in our painting appear to have the same local colors as the objects did in real life.

Friday, May 7, 2010

Beginning Steps for a Study

There are many ways to start out a painting.  The best method depends on the scale of the painting, the desired result, and the preferences of the painter.  For a smaller study, here is one method that I often use:
  1. Thumbnails - Make at least 2 small compositional thumbnails to work out the composition.  Keep the thumbnails small- 2 inches maximum on the long side.  If you have a canvas already make sure the thumbnails are the same proportion as the canvas.  The more accurate you are with this, the easier it will be moving forward.  If you don't have a canvas, then expand, contract, and shift the edges of the thumbnail around until you have a good composition.  Then buy or make a canvas that matches the proportions of your thumbnail.
  2. Initial Drawing - Choose a color of paint to draw with.  Any color can be used, though it will likely show up a bit through the layers of your paint so keep this in mind.  I recommend experimenting with different colors, but if you're not sure what to start with then try blue.  Mix whichever color you choose with white to a point where it is very light, but still visible from a good distance.  Use this color thinned down with turps to draw your thumbnail composition onto your canvas.  It helps to refer back to the thumbnail as you draw.  I tend to look at my thumbnail almost as much as the subject.
  3. Step Back - Step back and view your composition from a distance, and also try viewing your piece in a hand mirror.  Both of these are valuable tools to help you see the whole of your composition with some objectivity.  If space is limited and you can't step back, just use the hand mirror.  It's very good practice to step back as often as possible during the initial drawing, but it is critical to get a good look at your composition before you move on.
  4. Drawing Corrections - Mix your drawing color with white, but to a slightly darker value than in the previous drawing step.  Use this color to make corrections to your drawing.  The color you are working with should be just dark enough be distinct from your initial color, but still fairly light.
  5. Drawing Refinement - repeat steps 3 & 4 as necessary until you are satisfied with your drawing.  If your canvas becomes to saturated with paint to draw well, you can wipe it down with a cloth.  If you have made several edits in one color and it's becoming difficult to see your corrections, try switching to a different color paint.

A Comparison to Writing

When writing an essay, it's rare that someone just starts at the beginning, writes all the way through to the end, and then considers the essay complete.  Instead, one usually begins with a rough draft, and then through a series of edits you bring the rough draft to a completed essay.  While you will still make some effort to write a good first draft, you also understand that it will almost inevitably need editing and don't fret if something isn't quite working out right- you will be able to edit it later.

A similar attitude is useful when painting.  It's good to make a good effort on your initial drawing, but you can leave some pressure off yourself thinking that you have to nail everything right away.  If there's an area that isn't quite working, you just make a note and move on- rather than obsessing over the part you can't get.  You can always come back and get it later- particularly in oil paint which is very flexible.  This also helps prevent you from focusing too much on one area to the detriment of the rest of the piece.  This is kind of like writing with a word allotment and using too many words to make one of your points.

You can take this metaphor one step further and liken the thumbnail to creating an outline for your essay, where you lay out the major points quickly, and plan out the overall structure of the piece.  The thumbnail functions in a similar way- you don't want to get bogged down in all the details.  Just plan out what you fill in later in more detail.

Using a Viewfinder

When you are planning to fit your composition on a pre-purchased canvas, it can be very helpful to use a viewfinder of the same proportions as your canvas to aid you in both the thumbnail and drawing stages.  The simplest viewfinder is just a board with a rectangle cut out of it in the same proportions as your canvas.  A more flexible solution is to use two L-shaped pieces of board clipped together such that they form a rectangle of the right proportion.

[Photo to Come]

Alternatively, you can use a board with a square hole cut in it, and a second piece of board board clipped over the square such that it creates a rectangle of the correct proportion.  I prefer this kind of viewfinder because it easier to ensure right angles at the corners.

[Photo to Come] 

There are also various commercially available viewfinders.

It's worth noting that spending a little bit of extra time making sure your viewfinder is the correct proportion will save you lots of time and headache in your study.

Monday, May 3, 2010

Intro to Modeling

Modeling in painting refers to the process of making things look three-dimensional.  It's a place where intellectual understanding, observational ability, and paint handling skills come together.  As such, a large portion of modeling comes down to careful observation and years of experience handling paint.  The intellectual side is largely about understanding how light interacts with and reflects from surfaces, and how the eye processes those.  However, there are a few generalized concepts that can be helpful.

The Poster

The poster is a simplification of the value structure of your image into flat colors instead of smooth gradations. Each form is built up of myriad gradations, which can be difficult to comprehend. The poster simplifies these gradations made up of hundreds or thousands of steps of value into a much smaller and more manageable number of steps. How many steps is up to the artist, and can be quite flexible depending on subject matter and the technique being used.

The idea is to ignore the gradations at first and instead focus on the patterns that the gradations are making. Is it a smooth transition from light to dark? Does it get gradually darker most of the way and then suddenly shift more quickly at the end? Does it shift from dark to light and back to dark? How do all these shifts correspond to the contour?

Thinking of what the gradations are doing and putting them down in steps allows us to analyze the progression of values without worrying about the technique of making the smooth gradations. There are all sorts of ways to make the gradations later, but it's important to understand what's happening in them first.

 Example of digital Poster Study by Jason Rainville

Modeling Factors

The concept of modeling factors builds on the idea of the poster. Within an individual form, the artist decides on a certain number of steps to use in the poster, and these steps correspond to the progression of values one sees in chiaroscuro. The exact number of steps depends on the artist on the technique being used. For example, in more naturalistic techniques the artist might use 14 or more modeling factors, but in a more impressionist technique five or six modeling factors might be sufficient.

These six modeling factors are quite efficient at representing forms, and are a good base for realistic paintings:
  • Shadow - This is the area that is blocked from the light source by other parts of the same form or other forms.  It includes cast shadows.
  • Light - The area of the form generally facing the light.
  • Halftone - Between the shadow and light. While the light and shadow together establish the overall mass of the object, the halftone is critical for defining the more precise shape of the object.  The dividing line between the halftone and shadow is sometimes difficult to discern.  Casting a shadow across the halftone with a paintbrush or pencil can help distinguish the border- anything that is lighter than the shadow cast by the brush is still in halftone.
  • Highlight - A specular reflection of the light source. This differs from the light in that it usually will not appear where the form is facing the light, but rather in the spot where the light source would reflect if the form were a mirror.
  • Reflected Light - Despite its name this area occurs within the shadow.  The areas in shadow may receive small amounts of light reflected off other surfaces.  In a normal situation with one primary light, the reflected light will almost always be darker than the darkest part of the light on the same material, though it often appears lighter than it is due to simultaneous contrast
  • Depth (or Accent) - These are shadow areas where very little reflected light is reaching.  Depths will more frequently be found in the shadow or cast shadow, but also occur in the light where two forms or subforms overlap each other dramatically.  They're often found where two forms overlap, such as where the feet touch the ground, the neckline and cuffs where clothing is close to the form of the figure, and in crevices like the armpit and the crotch. Depths are quite valuable for showing one form sitting on top of another.

As few as two modeling factors can be used and still be quite effective. For very realistic renderings the artist might choose to divide each of the factors into 2 or more parts.

Note that for certain surface materials and certain situations some of these factors might not appear, or you might choose to leave them out. For example, matte materials may or may not exhibit a highlight. On fuzzy objects such as a tennis ball there will be no highlight. On very shiny or reflective objects some or all of the modeling factors may obscured by reflections. You might choose to leave out a highlight in situations where the technique you are using doesn't allow you to provide enough information to clearly identify the mark as a highlight.