Checking Drawing Accuracy in Photoshop

Garth Herrick · 03-01-2005, 12:03 AM

Hi Beth,

Good post questions!

You are correct to point out that one needs to take care to not have skewed or keystoned images, or the test drawing in the overlay will give false results. That is a whole another chapter to explain how to correct skew, aspect ratio, or keystone/perspective distortions. One of us should take the time to do that though. This is not rocket science either. As I just pointed out in another current thread about photographing paintings, I routinely take skewed pictures of my paintings (to avoid head-on glare), and then I remove the distortions in Photoshop (EDIT/TRANSFORM/DISTORT).

Beth if you can find a shortcut that does not use the calculator step, by all means share it with us! I know that one can change the scale of the overlay layer in EDIT/TRANSFORM/SCALE, but I have not seen how it is possible to constrain proportions in the process. If there is a way, then show me.

Thanks for resolving the question about PS Elements 2.0.

Garth

Elizabeth Schott · 03-01-2005, 12:30 AM

Quote:

That is a whole another chapter to explain how to correct skew, aspect ratio, or keystone/perspective distortions.

HA! Garth, now you are going to need to spend even greater amounts of time to teach me this!

Quote:

Beth if you can find a shortcut that does not use the calculator step, by all means share it with us! I know that one can change the scale of the overlay layer in EDIT/TRANSFORM/SCALE, but I have not seen how it is possible to constrain proportions in the process.

I must qualify the fact that I have no idea if this is correct, but it is what I do. Instead of all the calculations, you just make sure the two images you will be working with are the same resolution - dpi, before you paste one into the other, then just use the transform/scale feature.

Another trick is to take your reference and do a "path" out line of what you need to highlight, save the path. Then open your file of the painting and with them both open - just drag the saved path from the reference on top of the painting file and it will be saved there too. With the path tool selected (the pen or arrow just above) you will have an option to use the transform path/scale feature. Scale your path as needed and whammo, there's the mistakes or perhaps the perfection you were hoping for!

Garth Herrick · 03-01-2005, 12:40 AM

Quote:

Originally Posted by Elizabeth Schott

Another trick is to take your reference and do a "path" out line of what you need to highlight, save the path. Then open your file of the painting and with them both open - just drag the saved path from the reference on top of the painting file and it will be saved there too. With the path tool selected (the pen or arrow just above) you will have an option to use the transform path/scale feature. Scale your path as needed and whammo, there's the mistakes or perhaps the perfection you were hoping for!

Beth,

Please expand upon your "Path" method. I have never delved there before. (I want the ten page step-by-step instructions!)

Garth

Vianna Szabo · 06-02-2005, 02:21 PM

Just wanted to say a big "Thank you", Garth and Beth, for the information in this post. I tried reading instructions from a book to no avail and the "help" in my photo shop was most unhelpful. Thank you for breaking down the process so I can check my accuracy.

Vianna Szabo

Leslie Bohoss · 06-02-2005, 06:55 PM

Quote:

I know that one can change the scale of the overlay layer in EDIT/TRANSFORM/SCALE, but I have not seen how it is possible to constrain proportions in the process. If there is a way, then show me.

Garth,
hold down the "Shift" button while you "scaling" your picture layer. (PC)

bye

Richard Budig · 08-23-2005, 08:58 AM

Am I over simplifying, here? If I'm concerned that the head in my painting may be off from the original reference, I do the following:

Measure the height of the head on my canvas, trying to choose from top of hair to bottom of chin, but any measurement would work -- top of hair to bottom of nose. Then, in Photoshop Elements (I use Elements), I open my photo reference and twiddle with it until I get the "key" measurment the same as it is on my canvas. You can use the rulers at the top and side of the photo on your monitor to duplicate your canvas measurements. Then, print it out. Black and white will do. Then, take a piece of tracing paper, trace the key elements, and superimpose on the head on your painting.

The method Gart outlines at the beginning of this thread will be dead on, of course. But my very shortened version gets me to a place where I can check essentials. It's a quicky, but it can highlight the really out of whack places in your work.

Garth Herrick · 08-23-2005, 09:46 AM

Hi Richard,

Your approach is fine! I have an even simpler approach.

I sometimes simplify even further by tracing directly off the monitor. If the monitor is a flatscreen, it certainly helps toward this shortcut.

The following works for me: I'm using 1280 x 1024 resolution on a Mac.
1. Adjust the DPI (dots per inch) in IMAGE SIZE in Photoshop to 96 and.........
2. Scale your reference image to the same size as your painting, in inches or metric according to your preference (I have been going metric lately).
3. Press OK to accept these changes.

Now the reference on the monitor should be exactly to scale to your painting (and ready to trace if you wish).

Happy painting,

Garth