NOTE: This is from the thread Something about Genevieve , started by Jenni Nolen in the Pastel Critiques section. I did a digital analysis of her portrait which I think may be of general interest to all who use Photoshop to prepare reference images or need to check their portrait's accuracy, while in progress.
Always something new to learn in Photoshop!
As it happens, I just learned this new technique with the line tool, in Photoshop, with this digital demo. I measured both the photo and pastel from the chin to the eye. Then with a calculator I matched them both in scale. Overlaying the photo over the pastel in the best possible registration, I drew in the guidelines over the photo, then hid the photo layer to show the lines over the pastel. It's neat!
Garth
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Originally Posted by Julie Deane
How do you do it?
Garth -
Would you mind telling us Photoshop learners how you do those overlays step by step?
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Julie Deane
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Your Photoshop secret tutorial directions
Hi Julie,
It's not rocket science and once you get the hang of it, it's a lot easier and intuitive than it sounds.
Here goes:
1.) Download both desired source images the Forum artist has posted. I find I need to rename the images (any name that works for you), and specify ".jpg", in order to get the image to save as a usable file.
2.) Once downloaded, I open both files at once in Photoshop by dragging them together from my Finder window (I'm using a MAC! PC users find your own way.) onto the Photoshop icon in my Dock.
Both images should simultaneously open in Photoshop as two separate files.
3.) Under IMAGE SIZE, I immediately scale these two files to about twice their original size, maybe larger, for ease of use and precision.
OPTIONAL: For convenience, convert in PREFERENCES the measurement units to PIXELS (rather than INCHES or CM).
4.) Using the MEASURING tool (it's buried as an option under the EYE-DROPPER tool in the tool menu at the left), choose something to measure that works correspondingly in both images.
In this case I measured from the bottom of the chin to the middle of the right eye.
Click and hold down the mouse button at the start point of the measurement, and drag it to the end point, and release the button.
In the top menu, following "D:" ,will be the desired measurement readout, in this case, in pixel units. Write down the measurement result, and take the same corresponding measurement on the other source image and write down that result too.
Chances are these two numbers are not the same (if they are you've hit the jackpot and can skip the next few steps!).
Now you will want to match the scale of one image to the other:
5.) Decide which of the two source images you will now modify in scale to match the other. You will either be enlarging or reducing it.
Knowing which way you are going, use a calculator to divide the one written measurement result by the other.
If ENLARGING: divide the larger number by the smaller one.
If REDUCING: divide the smaller number by the larger one.
With the calculated resulting ratio, go to IMAGE SIZE again and pick any dimension listed, and multiply that number by the RATIO you just calculated.
With this next result on the calculator, go back to IMAGE SIZE and replace the dimension used for the last calculation with your new result, by typing it in to the (highlighted) box. Press SAVE and.....Voila!......
Both images will match in scale exactly.
6.) Now you want to copy and paste the one image over the other one.
Choose SELECT ALL to select all the image to be copied. Under EDIT, select COPY, and you will have copied the image to your virtual clipboard.
Going over to your other image that is to receive the overlay, select EDIT/PASTE, and you will now have successfully pasted the one image opaquely over the other, in a new layer.
Now you can edit the opacity of the overlaying layer, in the LAYER menu to the right. It will initiall read 100% in the numerical box. Click the small arrow to the right, and a slidebar will appear to allow you to modify this opacity setting to that which you desire, say 50% for now.
Now you can see both images about 50/50 apiece overlaid. With the MOVE tool in the left side tool palette, drag this top layer over the background layer until you register a good match (in this example we are matching both right eyes until they perfectly coincide and register as one). Ideally you will now see most features manifest in their perfection or imperfection, superimposed.
7.) Now go back to the LAYERS menu and reset the opacity back to 100%.
Important OPTION if you are painting lines with a BRUSH: Open a new LAYER/NEW/LAYER. This will be called LAYER 2. You can draw with the BRUSH any outlines or key registration points you wish onto this overlaying layer.
If you use the LINE tool (as I did), every straight line segment you add will automatically generate it's own separate LAYER! I generated over 50 more layers with all these angular connecting lines!
Above all, remember that the pasted in image layer is called LAYER 1. You will later be going back to it. All the added line segment layers will be LAYER 2, 3, 4, etc,......
With a BRUSH or LINE tool, whichever method you are comfortable with, draw some outlines around the key features you want to compare.
8.) Going to LAYER 1, select it and toggling the EYEBALL icon to it's left, you will hide that layer from view, revealing the other background source image and the verity or inaccuracy of it as evidenced by the colored outlines you just drew and overlaid.
9.) LAYERS/FLATTEN this image (you will discard the hidden layer, for now). FILE/SAVE AS this file as a new name, whatever works for you.
This is the saved image that will show all the errors and inaccuracies.
10.) In HISTORY, back up a step or two, to the historic state in the process just prior to when you hid LAYER 1. Select that point of history, and you will be back where you were earlier with all the multiple layers.
11.) Now once again, do the LAYERS/FLATTEN to the image in this state. Now once again, FILE/SAVE AS with a separate distinct file name.
This is your other saved image that shows the guiding painted lines in total agreement with the image, because this is the image you used to draw those lines.
12.) Resize and SAVE AS both these saved files to the sizes and standards needed for posting back in the FORUM, Post and upload the images, and write your descriptive justifying blurb, and you're Done!
When all this is second nature it can be accomplished in a matter of a few minutes of your time. It's not really that big of a deal.
I hope this helps!!!
Garth
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