Knitting a Picture – Photos to Color Charts Part 3

Where We Are So Far –

Originally, I saw this really great image on the internet and I wanted to wear it.  Because I’m a knitter, I wanted to wear it on a sweater that I knit.  Because I might be a little bit knitting/technology obsessed, I thought that I could learn to make a chart for the image all by myself on the computer, then write a tutorial for it so that any one else equally motivated would have a head start on making their own charts.

So far, I’ve written a tutorial on converting simple black and white shapes to a chart, a tutorial on converting abstract color images to charts, and then there’s the tutorial you are currently reading about converting a normal picture of a coffee cup to a chart you could knit into a sweater, or a blanket, or a pillow, or a pair of socks.

Just in case you like to express your affection for coffee in a way other than drinking multiple café mochas every day.

You Will Need the Following:

  • A high quality digital photo copy of the image you want to chart (don’t use the original in case something happens and the original is accidentally erased or permanently altered), preferably one that is very simple with two colors, similar to my example.  For two color images click here.  For images with abstract color shapes click here.
  • GIMP photo editing software – in theory another photo editor will work as well, but the instructions below are GIMP specific.  For those of you who don’t have GIMP, it is free photo editing software, Mac and Windows compatible, and very, very powerful (read tricky to use).  For those of you who are already thoroughly familiar with Gimp’s capabilities and are confident about what they are doing, I applaud you.
  • The ability to take a screen shot of just part of your computer screen (I use the on my Mac)
  • A printer
  • Foreknowledge of the size chart you want, the gauge in which you will be knitting, and the number of different colored of yarn you intend to use.  Note: if you use a small gauge with a large chart size, the resulting knit design will turn out better than if you use a large gauge with a small chart size.  The more different colors you decide to use, the more accurate the image will turn out.  

Some Introductory Explanation:

This is a fairly subtle image: a glossy white coffee cup and saucer on a white background, filled with brown coffee and casting a gray shadow.  The basic colors are white, gray, and brown.

If I change the background color from white to black, the image will show up much better, so that is one major change I will make to my chart.

On closer inspection of the photo, there is quite a bit of reflection on the outside of the cup and on the surface of the coffee.  Reflections don’t show up well in knitting, so I will need to alter that as well.

While all the shadows look gray, there are some differences in just how dark the shadows are around the coffee cup and saucer.  I have decided to change them to just one color of gray because I don’t want to be carrying a huge number of strands along the back of my knitting.

So the basic plan of attack is: separate image from background, separate and limit the colors to remove complicated reflections and shading, then superimpose a grid on the top to make it knit worthy.

Fun Stuff!

The Instructions –

1. Read ALL of these instructions first.  Do not attempt to work along with the instructions.  Some prep work is mentioned in the middle because that is where it contextually made sense to put it.

2.  Open the GIMP program on your computer.  To download GIMP, and for help using it visit this site

3. Click File > Open Image and select the image you want to convert to a knitting chart.  The image should pop up in the editing window.

4. At the bottom of the image window next to the zoom display is a tab showing what measurement system the window is using to show the size of the image.  Change the tab to show inches.

5. Change the zoom to read 100%

6.  In the header bar, click Image > Scale Image and a new window should open

7. In the Scale Image window, change the width to the number of inches desired, and hit enter.  The height should change automatically.  Click the Scale button in the lower left corner to alter the image.  Make sure that the resulting size of the chart matches the desired size by looking at the editing window and making sure the edges of the image line up with the desired inch measurement.  Note:  If you are having trouble viewing the whole image now, in the header bar click View > Zoom > Fit Image in Window, and you should be able to see the whole image once again

8.  In the top header bar, click Tools > Selection Tools > Free Select.  This turns your cursor into a ‘pencil’ which you can use to select just the part of the image you want to use in the chart.  For this tutorial, we will use the free select to get rid of the white background so we can see the coffee cup better.

With the cursor, while holding down the left mouse button, carefully outline the part of the image you would like to use as a chart.  You can do this either by carefully drawing around the edge or by clicking like crazy all the way around the entire shape until you have made a complete circle back to the beginning.  Then click the little yellow dot where you started, completely selecting the shape and turning the line you drew into a closed dotted line.  Make sure you draw or click as accurately around the shape as possible, because anything you include on the inside of the ‘circle’ you just finished making will show up in the finished chart.

9.  In the top header bar, click Select > Invert.  This selects and ‘highlights’ everything we don’t want in the finished chart so we can delete it in the next step.

10.  In the top header bar, click Edit > Cut.  Everything we aren’t interested in knitting should disappear.  If it looks like the image hasn’t changed, try clicking Colors > Invert in the top header bar.

IF YOU MAKE A MISTAKE:  It is very easy to accidentally click something and have the whole image disappear, so it is very important to keep only the part of the image you don’t want selected while deleting and inverting.  If the image is incorrectly selected, the part of the image you do want to keep may be deleted or altered.  If this happens, then undo it by repeatedly clicking Edit > Undo in the top header bar until the image looks okay again.  Then repeat steps 8 through 10, making sure that you invert the selection properly in step 9.

11.  In the top header bar, click Select > Invert to reselect the part of the image you want to keep.

12.  In the top header bar, click Image > Mode > Indexed and a new window should open.  Make sure that ‘Generate Optimum Palette’ is selected.  In the field next to ‘Maximum Number of Colors’, enter the number of different colored yarns you intend to use.  In the example image, I chose to use 4 different colors – white, light tan, brown, and black.  Click the ‘Convert’ button in the bottom left hand corner of the window to change the image.

Now is a good time to do a quick evaluation of your altered image and make a mental note of any alterations you plan to make when actually knitting the graph. For example, after converting the colors I decided that there were some areas which would look better if I embroidered them onto the knitting rather than trying to knit them as shown; such as the brown line at the base of the cup on the saucer.

Since curves don’t always adapt well given the linear nature of knitting, I plan to embroider a line around the outside of the shape to add depth and smooth out the lines.

I also plan to ignore the highlights (white dots) in middle of the coffee cup.

13.  If you have followed the other tutorials, then the rest of this should be old hat: adding a grid to the chart and printing it.  In the top header bar, click View > Show Grid and a grid should appear on top of your image.

14.  In the top header bar, click Image > Configure Grid and a new window will open.  Under “Appearance”, change the foreground color to black and the line style to solid.

15.  In the Configure Grid window under “Spacing”, you will need to enter numbers which reflect the gauge of your knitting project.  Most projects give the gauge in four-inch increments, for example: 32 stitches = 4″; 30 rows = 4″.  To convert our example measurement for use in GIMP, we need to dust off some third grade fractions.

First, divide the number of stitches by the gauge swatch measurement, and the number of rows by the gauge swatch measurement.  Using our example measurements:

32 sts ÷ 4 inches = 8.00 sts per inch

30 rows ÷ 4 inches = 7.50 rows per inch

Second, divide one by the new stitch number, and one by the new rows numbers.

1 inch ÷ 8.00 sts = 1 stitch 0.125 inches wide

1 inch ÷ 7.50 rows = 1 stitch 0.133 inches tall

Enter the resulting decimals into the width and height fields in the Configure Grid window.  Tip: If one field insists on changing with the other, try clicking the little link icon in the bracket beneath the width and height fields.  When the link looks ‘broken’, try re-entering the decimals. 

Click the OK button in the bottom left hand corner of the Configure Grid window.

16. Nearly Finished!  Because GIMP won’t export the image with the grid, now is the time to pull out your screen shot skills and put them to use.  Take a screen shot of the image inside the editing window and save it in a printable format somewhere on your computer you can find it, e.g. a .pdf on your desktop.

17.  Find your newly created .pdf and print it.  That’s it.  Your chart is done.  Each square is equal to one stitch.  If some of the lines are difficult to see, use a ruler to go back over the lines with a pencil.  If you made any mental notes between steps 12 and 13 about how you want to knit the graph, I’d recommend jotting them down on the back or bottom of the graph just in case life happens and you don’t get around to knitting your new chart for a while.

The last tutorial will deal with turning Andy Warhol into a sweater chart.

Happy Knitting!

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