Designing Scrollsaw Patterns
with Paint Shop ProX

Part 5


Resizing and More
Conversion Techniques

You will be using the following images from the image downloads in this lesson:

In the last tutorial I mentioned that we would be discussing resizing in a later lesson, so let's go ahead and address that subject now.

Computer graphics are of two types: raster or vector and it is important to understand the differences between the two data types.

Most, if not all the work that you will be doing when creating scrollsaw portrait patterns will be using raster images. When resizing these images we are concerned with two aspects:
  1. Image size is represented by the physical dimensions of the image. In Paint Shop Pro you define image height and width in pixels, inches, millimeters, or centimeters. This is done when you create a new image or when resizing the current image.
  2. Image Resolution is measured in pixels per inch (ppi) or pixels per centimeter. Lower resolutions can cause pixelation, or large pixels that produce coarse output. Higher resolutions can increase an image's memory requirements without producing a proportional increase in its quality.

It is important to understand how resizing affects image pixels.

Pixels have no set physical size. Each pixel represents one area of a single color. When an image is resized, the number of pixels in the image may be reduced or increased, which causes the image to be resampled. Resampling changes the file size.

Print resolution is the number of pixels per inch. More pixels per inch (ppi) create smaller printed pixels and a smaller printed image. Fewer pixels per inch create larger printed pixels and a larger printed image. Resizing can change the resolution of the image while preserving both the number of pixels in the image and the file size.

Choosing a resampling type lets you choose how the image is resampled. However, in most cases, it is best to use the default setting, Smart Size.

Ideally, we would start with a photo that was near the same size as the desired finished pattern. This photo could be scanned in at a high resolution and the resulting pattern should retain nice details. However, such is not always the case. Many times we are asked to make a pattern from an image posted on the web at a low resolution as well as of inadequate physical size. This type of starting point will result in an inferior pattern but some improvements can be made by resizing.

No doubt you have come across a pattern posted on the net that you think that you would like to cut. The pattern may look fair but be physically too small; such as the pattern below.

But, after resizing the pattern to the proper size, you find that it is so distorted and jagged that the pattern is impossible to follow; as in the graphic to the right.

Of course, this is not the type of patterns that we want to produce. We want to design quality patterns.

(Disclaimer: the above was one of my first attempts (blush, blush), just wanted it known that I am not picking on someone else’s work here. On the other hand, you will routinely find this type of work posted, and sadly to say, I have also bought patterns that were equally as inferior in quality)

Resizing within 25% of the size of the original will usually result in little distortion. If an adequately sized original image needs to be cropped this should cause no problem either. But usually the original is too small and will need to be enlarged.

The following exercise illustrates the relation between pixel resize and physical resize as well as a smoothing technique that may be used to smooth out some rough areas in a pattern.

For this exercise you will need to use a printer with black ink and three sheets of paper. The results of this exercise are for illustration purposes only.

Start PSP and open the "line.jpg" image.

Now click "Image Information" on the PA Bar. Here we learn that the physical dimensions of this image is 133 by 170 pixels or 1.773 by 2.267 inches. We also learn that the image is based at 75 pixels per inch, with a color depth of 8bits. Click "OK" to close the "Image Information" window.

This image was 2 color before being saved in the .jpg format. When an image is saved in this format the color depth is increase to 8 bit color and in the process varying shades of gray were introduced.

Now let's assume that this image is a pattern that we want to cut. We want the finished cutting to fit a 8" X 10" frame, so we will resize it to approximately 7" X 9" to allow for some border.

Click the "Resize" icon on the PA Bar. PSP8/9 We are presented with the "Resize" dialog window.(right)

The sequence which changes are made in this window are somewhat critical, so I will outline that sequence here:
  • First, using the drop down list, change the settings in the lists that are marked with the red dots to match the graphic to the right.

  • Next, make sure that all the boxes indicated by the green dots are checked. Important: the box must remained uncheck by "Maintain original print size.

  • Now change the dimensions to match those in the graphic; blue dots.

  • Click "OK"
Go to Window>Fit to Window. Click "Threshold" on the PA Bar then "Default" and "OK". This returns the image to 2 colors.

Not Pretty!

What we would like to have seen would have been three sections of a nice smooth black line crossing the page diagonally. Rather, it is a jagged mess.

Although not too pretty, we can try to smooth the lines up some. Pick up the paint brush tool that we created in the beginning tutorials, set to "round", size "10", then increase the pattern by zooming to 100%. Now using either black or white paint, smooth out the top left section of the pattern, the part that is marked with one white dot. Don't worry too much about keeping the line straight, we just want smoothness.

When you have finished smoothing just this section of the pattern, click the "Print" icon on the PA Bar, and print out the pattern, at 100% portrait. Mark the printout as #1.

The smoothing improved the appearance of that part of the line some, but let's see if we can do a little better.

When we resized the pattern just above, we only resized the physical dimensions. Now, we will do another resize, but this time we will be increasing the resolution (ppi) to 300 pixels per inch.

On the PA Bar click the "Resize" icon again.

When changing the resolution (increasing or decreasing) of an image the sequence is a little different than described above. First you will need to check the box by "Maintain original print size", (red dot). Also, make sure that the "Resample using" box is still checked. The other check boxes will be inactive now.

At "Resolution" (blue dot) change the settings to read "300".

After assuring that all the other boxes match those in the graphic at the right click "OK".

Please Note: If this were an actual pattern that you were working on, it would have been in the .pspimage format. In most cases, the pspimage format requires a much higher file size than a jpg . When the image is increased in dimension and resolution to this level a tremendous amount of your computer's memory resources are in use. If you are using a older computer with limited memory, I would recommend turning off the "Undo" function before increasing the resolution level to "300". To turn off the "Undo", go to File>Preferences>General Program Preferences> then under the "Undo" tab, uncheck "Enable the undo system". Don't forget to turn the "Undo" back on when going back to a lower "resolution".

OK, with the image resolution set to "300" let's turn our attention to the center portion of the black line (2 white dots). Although a lot higher resolution than before, the line is still just as jagged.

But wait....

Zoom the image to 100% and adjust so that the center of the line is in the screen. Go to Image>Count image colors and verify that the image is still showing only 2 colors. If not then click the "Threshold" icon and "Default" and "OK".

Pick up the same paint brush again, set the color to either black or white and smooth that portion of the line just as you did the top portion earlier. Hint: increasing the size of the brush to "20" or so will make the job easier.

Notice how much easier it is to smooth the line now without leaving rough edges.

Again, don't worry about keeping the line straight, we just want it smooth. Rarely will you have many absolutely straight lines in a pattern, but you will have many that you will want to be nice and smooth. I will show you later how to make a perfectly straight line in a pattern should the need arise. It's a lot easier that you would expect. After smoothing this section of the line as good as you can, print out the image again, still at 100%, portrait; label this copy - #2.

There is one more step in this exercise before we move on to something else.

In this step we want to return the image to "75" pixels per inch resolution but leave the physical dimensions as they are.

The settings in the "Resize" dialog window will remain exactly as they were when we increased the resolution with the exception of changing the Resolution to "75" (blue dot).

If all the other settings and check marks match this graphic click "OK"

Now you will need to print out 1 more copy of the image just as before; 100% portrait and label as #3.

Rather than get bogged down in a lot of theory here, let's just study the results of what we have done, and learn from that.

In our #1 example we were able to smooth the lines somewhat by filling in between the jags with black paint or by knocking the points off the jags with white paint, with fairly good results.

After increasing the resolution to "300" we had a much improved paint brush to work with. The jags were still present after the resize, but because we had a smoother brusher (4 times the number of bristles as before) we were able to obtain a much smoother finish to our line.
Then finally, we reduce the pixels per inch back down to "75". This resulted in some lost of definition to the center line but it still remained better than the first portion. However, it is important to notice here that the last portion of the line, the portion we did nothing to, remained virtually the same in each of the 3 examples.

The point is, you cannot improve the quality of an image substanstially by simply increasing the resolution. We were able to improve the quality of the image by using a "tool" whose qualities were improved by increasing its resolution. thereby, giving us a better defined finish than we had previously.

An example: suppose you were spreading butter on a piece of bread. Could you get the butter smoother by using the prongs of a fork or the edge of a knife? The knife, of course. The bread and the butter remain constant but the effects are changed by changing the tool.

The next obvious question would be, why not just created and save everything at 300 ppi?

This could be and is done. An image can be scanned into the computer, converted, finished and printed at this resolution. However, files for this type pattern are generally much too large to be posted on the internet.

Personally, I prefer converting all my patterns to pdf and if you interesting in learning how to do this, (the software is free) we will be talking about that in a later tutorial.

I know that this discussion has been long and maybe seemingly unimportant, but the further you go into developing scrollsaw patterns the more you will appreciate the topic and you will want to come back and review it from time to time. Neither is this topic cut and dried. There are several opinions that are voiced and I would invite you to hear them all.

Go ahead and close the line.jpg image and open the Prairie Dog.jpg., then "Save As" a .pspimage.

In Part 4 we learned how to use the "Threshold" adjustment function to perform a conversion. In this tutorial we will carry the Threshold function a bit further by introducing two modifiers; the Gaussian blur and the Sharpness functions. These functions may be applied to an image to modify the conversion output preformed by the Threshold adjustment.

As their names imply, the Sharpness function: sharpens the image to a degree and the Gaussian blur: blurs the image. There are times when both the functions are beneficial to us, and though seemingly opposites sometimes they can be used together to render a better image base. And, just as was the case with the threshold adjustment, the use of these functions will be determined by your interpretation of an image and what you think that needs to be done to improve that image.

Let's prepare our image by resizing it to a proper cutting size, which would be enlarging by about 115%. This will give you a print out of approximately 7 X 9 inches. Now we need to increase the color depth to 16 million colors or 16 bits then click the icon to duplicate the layer.

The first thing that you will want to do with a new image after doing the prep work, is to do a "dry run". That is execute the Threshold adjust command and manipulate the settings to locate where any trouble spots may be in the image. Locating these trouble areas will become easier with time and practice.

I have taken this "dry run" on the Prairie Dog image up to above 180 on the threshold scale before getting a good average definition. However, by the time the threshold had been advanced that far, other parts of the image begin to become distorted. This is a good candidate for the "sharpness" function.

When you have done your dry run, click "Cancel" rather than "OK". Click on the drop down menu by "Sharpness" and click "Sharpen More". (just "Sharpen" general does not affect an image enough to be effective)

Now, execute the "Threshold" adjustment command again. This looks much better. I like the settings around 150 to 155 best. When you find a setting that you like click "OK" and then it's back to using the paint brush tool to finish the pattern.

The graphic on the left shows the conversion after executing the "Sharpen more" command and a threshold setting of "153". The graphic on the right is my final version of the pattern.

When finishing a pattern like this, that is, one with an excessive amount of black lines and specks, I like to eliminate a large percentage of those black markings and make the ones that are left heavier and more dominant. I feel this makes a better finished piece plus makes the pattern much faster and easier to cut.
When you have completed the Prairie Dog pattern, open and prep the Swamp Rabbit image. Using this image, we will experiment with Gaussian blur.

A Gaussian Blur is a general purpose blur filter. This removes fine image detail and noise leaving only larger scale changes. Gaussian Blurs produce a very pure smoothing effect without side effects. I find the Gaussian blur to be most helpful when converting animal pictures. The blur tends to smooth the fur or hair making it more easily patterned.

The graphic below shows the Swamp Rabbit image converted at no blur and then two levels of Gaussian blur each using the same threshold adjustment settings.

This gives you the general idea of what the Gaussian blur does to an image. The tool is more valuable when used on an actual photo graphic but the results are similar to this example.

To use Gaussian blur, click the icon on the PA Bar, then in the dialog window adjust to the desired settings. Usually, the default setting at 1.00 radius is adequate but occasionally you may need a higher setting of 1.50 or possibly 2.00. I have found that too much detail is lost at settings above 2.00.

At this point, time spent by just experimenting with the Gaussian blur and the sharpening functions would be of much more advantage to you than anything I could say. So as we said before: Practice Practice Practice!! I would like for you to post at least one of the patterns, either the Prairie Dog or the Swamp Rabbit in the Part 5 Projects folder at Pattern Academy before going on to the next tutorial. Or if you rather, try the Bear image.

Practice Project: Open the Bear.jgp image and convert to a pattern using the techniques explained above. The bear makes a really nice pattern when just a small amount of Gaussian blur is applied.

In Part 6 we will begin working with photos starting with background removal techniques.

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