Trend recognition: higher highs and higher lows?

Hi

I have a question regarding studying a stock price chart and trying to find an uptrend by identifying higher highs and lower lows.

For example when you try to find a higher high, do you use the high price for the day, or the close price?

Conversely when finding a lower low, do you use the low price for the day, or the close price?

I know this is easy to see on a chart, but I am working on software where I'm trying to find trends and am not sure which price to use.

Any help would be appreciated.

Thanks

Trend recognition: higher highs and higher lows?