Scan ElliotOscillator histogram to select the highest peak of each wave over 70

What you have requested is not a scan. I see from the attached PDF doc that you want to mark the peaks of the ElliotOscillator histogram, only when they exceed 70. This is not a scan. A scan is a true/false filter criteria that returns a list of stocks that match the filter criteria.

So you are asking for a chart study. The simplest solution would be to place a line on the ElliotOscillator at the value of 70. Then change the color of the plot for any values above that line.

This can be accomplished with very minor changes to the ElliotOscillator that comes with Thinkorswim. However the values are highly dependent on the price of the ticker symbol being charted. For example on a chart of MOS trading around $10 the histogram rarely goes above 0.7. But for a larger priced stock like AMZN trading around $1990 the histogram easily surpasses 40-50 range.

So your request is only going to fit the most narrow focus you could ever imagine. The value you select will be good for only a handful of ticker symbols. So the very basis of your request is a bit misguided. You really need to have some other method of identifying the peaks because using a fixed value for this chart study is very poor design.

However, here is the code that gets the job done:

input shortLength = 5;
input longLength = 35;
input peakLimit = 0.70;
def price = (high + low) / 2;
plot elliotOscillator = Average(price, shortLength) - Average(price, longLength);
plot zeroLine = 0;
plot limitLine = peakLimit;
elliotOscillator.SetPaintingStrategy(PaintingStrategy.HISTOGRAM);
elliotOscillator.SetLineWeight(3);
elliotOscillator.DefineColor("Positive", Color.UPTICK);
elliotOscillator.DefineColor("Negative", Color.DOWNTICK);
elliotOscillator.DefineColor("Peak", Color.MAGENTA);
elliotOscillator.AssignValueColor(if elliotOscillator > limitLine then elliotOscillator.Color("Peak") else if elliotOscillator > 0 then elliotOscillator.color("Positive") else elliotOscillator.color("Negative"));
zeroLine.SetDefaultColor(getColor(8));

Edit: In response to a request in the comment section below I will also provide an option to change the code to identify negative extremes. You can change one line of code to get it to perform the exact opposite as the original. Here is that line of code, modified to find extreme negative values. If you make this modification then you should use negative values for the user input named "peakLimit".

elliotOscillator.AssignValueColor(if elliotOscillator < limitLine then elliotOscillator.Color("Peak") else if elliotOscillator > 0 then elliotOscillator.color("Positive") else elliotOscillator.color("Negative"));