The image data captured by your camera is written in flash storage, either in a removable microSD card, or in its built-in QSPI flash memory.  A microSD card can be removed and accessed with a standard microSD reader.  The onboard QSPI flash should appear as an external drive to a regular computer, when the board is connected by USB.  Either way, go ahead and plug your device into the computer where your Processing code resides and get ready to copy some data.

As you begin exploring the flash drive, you should see a folder in the root directory named MLX90640.  This is where the camera sketch stores all its files.  Open it and have a look.

Two things you might find in this folder are BMP files and more folders, all with names containing serial numbers.  The folders should contain even more numbered BMP files.  The BMP files are what we'll be copying and pasting, one group at a time.  Any sequence of images is a good choice to start, either in the MLX90640 folder or in one of the dir##### folders.  Decide on a group.

Since the camera sketch is active, it can capture more BMP images while connected, but the Arcada functions prevent new captures from being accessed while running. That's normal, and it prevents errors. Just restart the camera sketch to open your latest images.

Now open the processing sketch called ConvertBMPinspector01, but don't run it (yet).  Instead, open its home folder from the menu by selecting Sketch>Show sketch folder.  Your operating system should present a file management window showing the filename of the sketch itself.  Next to that, you will need to create another folder named data, if none already exists.  Open that data folder, because that's where your BMP images should go.  It's a simple matter of copy/paste, and a set of numbered files all named frm#####.bmp should be the only things pasted into the data folder.

(These steps will happen before using the other two Processing sketches, too.)

Using ConvertBMPinspector01

Go ahead and run the ConvertBMPinspector01 sketch.  You should see a window open showing some numeric values, a thermal image magnified and in color, and some control buttons beneath.

The screen is now yours to explore.  The statistics on the left show file and temperature details like the filename, the frame count in a sequence, a time stamp showing elapsed seconds of runtime at capture, and three exact temperatures detected by the sensor (hottest pixel, coldest, and center pixel [16, 12]).

With the pointer you can hover over the image itself and make the color and approximate temperature of any pixel appear in a rectangular frame below.  The XY location of the pixel is shown as well.  Whereas the left-side temperatures are shown exactly as measured, the interactive pixel temperatures are approximate, since they're recomputed from 8-bit color values.  You can see this by comparing pixel[16,12].  The temperatures returned are not the same, but pretty close.

Sometimes images are captured using a preset color range, but actual temps can fall outside that range.  The display will indicate colors that are maxed out (or "minned" out) with > or < symbols.  The left-side numbers are not affected by this.

The control buttons at the bottom are pretty straightforward.  The leftmost toggles between temperatures displayed in Fahrenheit or Celsius.  The rightmost will cycle between several false-color palettes to enhance detail visibility.  The buttons in between are for stepping through a sequence of image files in small or large steps.  The keyboard can manage these controls as well, using the , . < > m / keys.  (The sketch can be used to inspect a single image, but a sequence of images is more fun.)

This guide was first published on Mar 27, 2020. It was last updated on Jun 16, 2024.

This page (Getting the Pictures) was last updated on Mar 08, 2024.

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