Tracing on an ipad.                  © WilliamWiseArt.com

If you want or need a “master drawing” from which to do multiple paintings, consider drawing your master on tracing paper. If you use your ipad to display your reference photos while you paint, you can also freeze or lock an ipad screen so you can create a 1:1 drawing or tracing to transfer on to watercolor paper or to any painting surface. The method I will describe is a kin to the classic low-tech techniques using the grid method. Other classic methods to consider is to project onto a wall, tracing over a full size photo, or tracing directly on your computer monitor. Images on a monitor don’t move when you touch them but they did on the touch screen of an ipad.

NOTE: For this to make sense you need to follow along with the ipad in your hand.

To freeze the screen on your Ipad (or iphone) so you can trace an image, you need to activate the feature called Guided Access. You can do a search on Guided Access for lots of YouTube videos for more info.

Guided Access on an Ipad or Iphone.

1. Click – Settings, then Click > General > Accessibility, then scroll down and turn on – Guided Access.
2. Below Guided Access on the > Accessibility screen > press Passcode Settings. Set a pass code (make it very simple, like 1111). This does not need to be the same as your main security code.
3. To activate the Guided Access feature hit the round button on the face of the ipad 3 times quickly to turn the lock on, then 3 times quickly to unlock. (Not the power button on top)
4. In the bottom middle shut off Touch, The screen will go gray. This shuts off the ability to touch the screen!!! That is what you are after.
5. At the top there is End, that shuts off “Guided Access”,  Resume brings you back to the screen so you can touch it again without moving the image.
6. To get back to the “Guided Access” screen you need to press the button 3 times and put in your password. You will be entering the password a lot. If you want to change it to something easier now go back to step 2.
7. When you have Guided Access open there are some options you can disable. (Note: this feature it is designed to keep your kids from buying furniture from your phone when you only wanted them to play a game!!). On the bottom, see Hardware Buttons. I just turn on Keyboards. You can figure out the others if you want.

Practical Use for this app and drawing.
Let’s say you want to simply draw/trace 1:1 what is on your screen. (You won’t do this but take these baby steps first.)

1. Open a photo as normal. You can’t resize it but you could trace what is on the screen.
2. Instead, open a photo in your Photo Edit App. Resize or Edit as normal within your app!
3. To lock the ipad touch screen for tracing, press the round button 3 times. The ipad screen is now frozen to allow you to trace on the screen! Still only 1:1 what is on screen.
4. To End this, press the round button 3 times, enter the passcode.
5. Press End on the top of the Guided Access screen or resume…

These steps will probably be very similar with your favorite editing app.
Camera Lucida application: Available from the Apple app store. Beware: There seems to be another app with the same name. The one I use most is by Peter Moeykens and currently costs $9.99, + the In-App purchase of $5 to auto-correct for perspective.  NOT the free app.
Using Camera-Lucida to trace a photo onto tracing paper or equal.

1. Open a photo, > book symbol in lower left.
2. Move your image around, resize it, pinch, etc. The size of the visible image on a normal ipad tablet’s screen is a very close ratio to a large 11×14” or 15”. So right now imagine this is what it will look like when you paint it FULL size. (It is a bit in the weeds right now, stick with me)
3. When you have it cropped and positioned on the tablet screen as you will want to paint it on your painting surface, Click the “computer disk” save button. This saves a resized COPY of the original image.
4. Touch the middle “drawing hand” button. Move the slider to far right to make the picture clear. Touch the “Tool Box”. (You can change the image as you like with this app. I often use Posterize to see values. Try lots and save lots of these individual changes. You can delete the ones you don’t want later.)
5. To make a tracing drawing, in the tool box, at the bottom of the menu, select “Add Large Grid” > Save. This will put a 12 box grid (three wide by 4 long) on the NEW sized image you just made and it will be another, additional COPY!

To trace a large image: 
You can not see through or trace directly on to 140# (300GSM) Watercolor (WC) paper with the ipad. You must draw first on tracing paper (or equal) then trace on one of my easels, a window, or a lightbox. You need to follow along with a saved image with the 12 box grid and a piece of tracing paper for this to make sense as you read it.

1. Lay a piece of tracing paper onto your sheet of WC paper (or your canvas). Align the top left corners. Draw the outer edges of the WC paper (or canvas) on the tracing paper so you have a 1:1 reference on the tracing paper.
2. The first important steps of this drawing process is to make the first two marks on the tracing paper at the right size and location (see the 2.a below) to ensure your tracing will be in the right scale. Again you have a drawing on your ipad with 12 boxes. To get the first two reference/alignment marks on the tracing paper we need to determine and mark where the lower right corners of the upper left box and lower right corner of the middle left boxes (register locations) will be . These corners are FIRST located and marked on your tracing paper : The following are common example sizes.
   1. Measure for 11×14”. Long side, measure in and mark at 3 ¾” (7 ½” & 11”) Then divide the length by fourths. For 14” length measure down and mark at 3 ½” & 7″, (10 ½, 14”).
   2. For an 8×10” measure in from long side 2 5/8” and down from the short edge
      2 ½”& 5”.
3. Mark these two reference crosses at those intersections. These marks may change…
4. To trace a 1:1 image on to the tracing paper you must now enlarge the image on the ipad. Go back to the image in Camera-Lucida you just created with the grid.
5.  We will now be making the image on the ipad larger to match the size we want it on the painting surface. This gets in the weeds so be patient.
   1. Pinch your image on the ipad to make the size of the height of the grid square on the left side 3 ¾” tall (or very close). (for the 11×14” example in 2a above) That makes the size of the image on the ipad fit (1:1) your desired scale you want on your painting surface. Tip: You can mark 3 ¾” on a scrap of paper to use as a ruler.
   2. With one finger move the photo with the grid on the ipad to see all of the upper left corner square on the screen. (Don’t accidentally resize the image, if you do go back to 5a.) You should see two corner intersections. This is what we want to trace on the screen!!!!!!
   3. NOW, Tap the ipad screen button 3 times. That starts the Guided Access feature. The screen should be frozen in that position and touching the screen won’t move it.
   4. Line up the two registration marks on the tracing paper with the screen and use balls of Blu-Tack or kneaded eraser to hold your paper to the ipad so it doesn’t move. If the registration marks are off a tiny bit, remark the points exactly on the paper where they are on the screen. The screen now will be the main reference. You will use these marks to line up the rest of the register marks on the tracing paper.
   5. Begin tracing with a DARK pencil. You have to see these lines when you transfer it to the WC paper. Remember you are an artist. You don’t need every detail on this paper. You will refine the final drawing when you have it traced on your WC paper!!
   6. When you are done with that section, press the ipad button three times, enter your code, press “End” on the app in the upper left corner. This shuts off the Guided Access. Again WITH ONLY ONE FINGER reposition the image. Include the original two register marks in the image plus one or more corners. Press the ipad button three times and it is frozen again as in 5c
   7. As done previously, secured in place, accurately mark the additional new visible register mark(s). Then trace that section.
   8. You always need at least two register marks for alignment.
   9. When you are done you will have enough lines to transfer onto the WC paper or canvas.
6. There are many ways to transfer this to the WC paper. You can Tape it on the back and trace on a window, or use some transfer paper (not carbon paper) and trace over the paper, etc. Please read my article “Before you Paint, Reference Photos and Pencil Lines”. It emphasis that if your lines will be seen in the painting, they need to be interesting!!!

Good luck, Bill
Edited 27 Feb 2022, noted that there seems to be more than one Camera Lucida app., 8 Dec 2020, Created 25 Aug 19.