The camera alone can do plenty, but with the data it captures you can do even more. One way to explore your thermal images is to use sketches in a programming language from Processing.org that runs on a full-blown computer. There is an Adafruit tutorial on installing the Processing environment on a Raspberry Pi, and their website has links for Mac and Windows users as well.
The Inspector Sketch
Once you have the Processing package installed and set up, here is a sketch to download and try. Open a new sketch window, copy the following code and paste it there, and save it as ConvertBMPinspector01. Be sure you're working in the Processing environment and not in the Arduino environment. It's an easy mistake to make.
// ConvertBMPinspector01 - Read and enlarge a modified 32x24 24-bit gray BMP file,
// display an upscaled 256x192 BMP image in 256 colors.
// Ver. 1 - Fetch filenames and display BMPs in sequence.
// Add nav buttons and mouseover pixel temperatures
// This sketch does no checking for file compatibility.
// Only frm_____.bmp images from the thermal camera sketch will work.
// Any other files in the data folder will fail.
import java.util.Date;
byte b[], colorPal[]; // Buffers for input file bytes and for colors
int i, fileCount = 0, BGcolor = 48, colorMap = 1,
butnsX = 30, butnsY = 290,
offsetX = 153, offsetY = 6, // These value pairs control where the onscreen features appear
numbersX = 40, numbersY = 48,
probeX = 190, probeY = 210;
boolean celsiusFlag = false;
float fixedPoint[];
String[] filenames;
void setup() {
size(480, 360); // Size must be the first statement
background(BGcolor); // Clear the screen with a gray background
colorPal = new byte[1024]; // Prepare a 1K color table
loadColorTable(colorMap, 0); // Load color table, 1 == ironbow palette
fixedPoint = new float[5]; // A buffer for appended fixed point values
String path = sketchPath() + "/data"; // Read from the "/data" subdirectory
filenames = listFileNames(path);
fileCount = filenames.length;
i = 0;
if(fileCount < 1) {
println("No files found. Stopping.");
noLoop();
} else {
loadBMPscreen(i); // Read in the first frame for inspection
}
}
void draw() {
int sampleX, sampleY, pixelVal;
float sampleTemp;
sampleX = (mouseX - offsetX) >> 3; // Map mouse position to BMP pixel space
sampleY = 23 - ((mouseY - offsetY) >> 3);
noStroke();
smooth();
fill(BGcolor + 16);
rect(probeX, probeY, 180, 40); // Clear the interactive window space
if((sampleX >= 0) && (sampleX < 32) && (sampleY >= 0) && (sampleY < 24)) { // Mouse within BMP image bounds?
pixelVal = b[54 + (32 * sampleY + sampleX) * 3] & 0xff; // Read the 8-bit pixel value
fill(colorPal[4 * pixelVal + 2] & 0xFF, colorPal[4 * pixelVal + 1] & 0xFF, colorPal[4 * pixelVal + 0] & 0xFF);
rect(probeX, probeY, 180, 40);
fill(BGcolor);
rect(probeX + 10, probeY + 10, 160, 20); // Draw a colorized frame for the interactive temp readout
sampleTemp = (float(pixelVal) + 1.0) / 257.0 * (fixedPoint[3] - fixedPoint[1]) + fixedPoint[1];
if(!celsiusFlag)
sampleTemp = sampleTemp * 1.8 + 32.0;
fill(255); // Ready to display white interactive text
textSize(11);
text(sampleX, probeX + 154, probeY + 19); // Display X Y position
text(sampleY, probeX + 154, probeY + 29);
textSize(15);
text(sampleTemp, probeX + 60, probeY + 25); // Display temperature
if(pixelVal == 0 && fixedPoint[0] < fixedPoint[1]) // Pixel values clipped at bottom limit?
text("<", probeX + 40, probeY + 25); // Show out-of-range indicator
if(pixelVal == 255 && fixedPoint[4] > fixedPoint[3]) // Clipped at top?
text(">", probeX + 40, probeY + 25); // Same
}
noSmooth(); // Clear any highlighted buttons
stroke(0);
noFill();
for(sampleX = 0; sampleX < 8; ++sampleX)
rect(butnsX + sampleX * 52, butnsY, 51, 24);
sampleX = mouseX - butnsX;
sampleY = mouseY - butnsY;
if(sampleX >=0 && sampleX < 416 && sampleY >= 0 && sampleY < 24) { // Mouse over buttons?
sampleX = sampleX / 52; // Map mouse X to button X space
stroke(BGcolor + 64);
rect(butnsX + sampleX * 52, butnsY, 51, 24); // Highlight border around a button
}
}
void keyPressed() { // Load a different thermal BMP image based on keystroke
switch(key) {
case '.': // Next image
i = (i + 1) % fileCount;
break;
case ',': // Prev Image
i = (i + fileCount - 1) % fileCount;
break;
case '>': // 16 images forward
i = i + 16 < fileCount ? i + 16 : fileCount - 1;
break;
case '<': // 16 images back
i = i - 16 < 0 ? 0 : i - 16;
break;
case '/': // Last image
i = fileCount - 1;
break;
case 'm': // First image
i = 0;
break;
}
loadBMPscreen(i);
}
void mousePressed() {
int sampleX, sampleY;
sampleX = mouseX - butnsX;
sampleY = mouseY - butnsY;
if(sampleX >=0 && sampleX < 416 && sampleY >= 0 && sampleY < 24) { // Is mouse over button row?
sampleX = sampleX / 52; // Map mouse X to button X space
switch(sampleX) {
case 1: // First image
i = 0;
break;
case 2: // 16 images back
i = i - 16 < 0 ? 0 : i - 16;
break;
case 3: // Prev Image
i = (i + fileCount - 1) % fileCount;
break;
case 4: // Next image
i = (i + 1) % fileCount;
break;
case 5: // 16 images forward
i = i + 16 < fileCount ? i + 16 : fileCount - 1;
break;
case 6: // Last image
i = fileCount - 1;
break;
case 7: // Change color map
loadColorTable(colorMap = (colorMap + 1) % 5, 0); // Load color table
break;
default: // Toggle C/F
celsiusFlag = !celsiusFlag;
break;
}
loadBMPscreen(i);
}
}
void loadBMPscreen(int fileIndex) {
int x, y;
b = loadBytes(filenames[fileIndex]); // Open a file and read its 8-bit data
background(BGcolor); // Clear screen
enlarge8bitColor(); // Place colored enlarged image on screen
for(x = 0; x < 5; ++x) { // Rebuild 5 float values from next 4*n bytes in the file
fixedPoint[x] = expandFloat(b[2360 + (x * 4) + 0], b[2360 + (x * 4) + 1],
b[2360 + (x * 4) + 2], b[2360 + (x * 4) + 3]);
}
y = ((b[2387] & 0xff) << 24) + ((b[2386] & 0xff) << 16)
+ ((b[2385] & 0xff) << 8) + (b[2384] & 0xff); // Reassemble a milliseconds time stamp
textSize(10); // Print text labels for the frame stats
smooth();
fill(255);
text(filenames[fileIndex], numbersX + 5, numbersY + 40); // Show current filename
if(celsiusFlag)
text("Frame\n\n\nSeconds\n\nDegrees C", numbersX + 5, numbersY + 8);
else
text("Frame\n\n\nSeconds\n\nDegrees F", numbersX + 5, numbersY + 8);
text("Approximate temperatures based on 8-bit pixel values", probeX - 42, probeY + 52); // Show approximation disclaimer
textSize(15);
text(fileIndex, numbersX + 5, numbersY + 25); // Print frame number
text(float(y) * 0.001, numbersX, numbersY + 74); // Print time stamp in seconds
if(celsiusFlag) { // Show 3 temps in Celsius
fill(255, 128, 64);
text(fixedPoint[4], numbersX, numbersY + 108);
fill(255, 200, 64);
text(fixedPoint[2], numbersX, numbersY + 128);
fill(128, 128, 255);
text(fixedPoint[0], numbersX, numbersY + 148);
} else { // or show them in Farenheit
fill(255, 128, 64);
text(fixedPoint[4] * 1.8 + 32.0, numbersX, numbersY + 108);
fill(255, 200, 64);
text(fixedPoint[2] * 1.8 + 32.0, numbersX, numbersY + 128);
fill(128, 128, 255);
text(fixedPoint[0] * 1.8 + 32.0, numbersX, numbersY + 148);
}
noSmooth();
stroke(0);
fill(BGcolor + 24);
for(x = 0; x < 8; ++x) // Draw 8 button rectangles
rect(butnsX + x * 52, butnsY, 51, 24);
for(x = 0; x < 50; ++x) { // Paint a mini colormap gradient within last button
y = int(map(x, 0, 50, 0, 255));
stroke(colorPal[4 * y + 2] & 0xFF, colorPal[4 * y + 1] & 0xFF, colorPal[4 * y + 0] & 0xFF);
line(butnsX + 365 + x, butnsY + 1, butnsX + 365 + x, butnsY + 23);
}
smooth(); // Add text labels to buttons
fill(255);
textSize(15);
text("|< << < > >> >|", butnsX + 70, butnsY + 17);
if(celsiusFlag)
text("C", butnsX + 20, butnsY + 18);
else
text("F", butnsX + 20, butnsY + 18);
}
void enlarge8bitColor() { // Convert a small gray BMP array and plot an enlarged colormapped version
int x, y;
noStroke();
for(y = 0; y < 24; ++y) { // Count all source pixels
for(x = 0; x < 32; ++x) {
int pixMid = b[54 + ((32 * y + x) + 0) * 3] & 0xFF;
fill(colorPal[4 * pixMid + 2] & 0xFF, colorPal[4 * pixMid + 1] & 0xFF, colorPal[4 * pixMid + 0] & 0xFF); // Get color from table
rect(offsetX + 8 * x, offsetY + 8 * (23 - y), 8, 8); // Draw a square pixel, bottom up
}
}
}
void loadColorTable(int choiceNum, int offset) {
int i, x;
switch(choiceNum) {
case 1: // Load 8-bit BMP color table with computed ironbow curves
for(x = 0; x < 256; ++x) {
float fleX = (float)x / 255.0;
float fleG = 255.9 * (1.02 - (fleX - 0.72) * (fleX - 0.72) * 1.96);
fleG = (fleG > 255.0) || (fleX > 0.75) ? 255.0 : fleG; // Truncate curve
i = (int)fleG;
colorPal[offset + x * 4 + 2] = byte(i & 0xFF); // Red vals
fleG = fleX * fleX * 255.9;
i = (int)fleG;
colorPal[offset + x * 4 + 1] = byte(i & 0xFF); // Grn vals
fleG = 255.9 * (14.0 * (fleX * fleX * fleX) - 20.0 * (fleX * fleX) + 7.0 * fleX);
fleG = fleG < 0.0 ? 0.0 : fleG; // Truncate curve
i = (int)fleG;
colorPal[offset + x * 4 + 0] = byte(i & 0xFF); // Blu vals
}
break;
case 2: // Compute quadratic "firebow" palette
for(x = 0; x < 256; ++x) {
float fleX = (float)x / 255.0;
float fleG = 255.9 * (1.00 - (fleX - 1.0) * (fleX - 1.0));
i = (int)fleG;
colorPal[offset + x * 4 + 2] = byte(i & 0xFF); // Red vals
fleG = fleX < 0.25 ? 0.0 : (fleX - 0.25) * 1.3333 * 255.9;
i = (int)fleG;
colorPal[offset + x * 4 + 1] = byte(i & 0xFF); // Grn vals
fleG = fleX < 0.5 ? 0.0 : (fleX - 0.5) * (fleX - 0.5) * 1023.9;
i = (int)fleG;
colorPal[offset + x * 4 + 0] = byte(i & 0xFF); // Blu vals
}
break;
case 3: // Compute "alarm" palette
for(x = 0; x < 256; ++x) {
float fleX = (float)x / 255.0;
float fleG = 255.9 * (fleX < 0.875 ? 1.00 - (fleX * 1.1428) : 1.0);
i = (int)fleG;
colorPal[offset + x * 4 + 2] = byte(i & 0xFF); // Red vals
fleG = 255.9 * (fleX < 0.875 ? 1.00 - (fleX * 1.1428) : (fleX - 0.875) * 8.0);
i = (int)fleG;
colorPal[offset + x * 4 + 1] = byte(i & 0xFF); // Grn vals
fleG = 255.9 * (fleX < 0.875 ? 1.00 - (fleX * 1.1428) : 0.0);
i = (int)fleG;
colorPal[offset + x * 4 + 0] = byte(i & 0xFF); // Blu vals
}
break;
case 4: // Grayscale, black hot
for(x = 0; x < 256; ++x) {
colorPal[offset + x * 4 + 2] = byte(255 - x & 0xFF); // Red vals
colorPal[offset + x * 4 + 1] = byte(255 - x & 0xFF); // Grn vals
colorPal[offset + x * 4 + 0] = byte(255 - x & 0xFF); // Blu vals
}
break;
default: // Grayscale, white hot
for(x = 0; x < 256; ++x) {
colorPal[offset + x * 4 + 2] = byte(x & 0xFF); // Red vals
colorPal[offset + x * 4 + 1] = byte(x & 0xFF); // Grn vals
colorPal[offset + x * 4 + 0] = byte(x & 0xFF); // Blu vals
}
}
}
// Rebuild a float from a fixed point decimal value encoded in 4 bytes
float expandFloat(byte m1, byte m2, byte e1, byte e2) {
int fracPart;
float floatPart;
fracPart = ((e2 & 0xff) << 8) + (e1 & 0xff); // Reassemble 16-bit value
floatPart = (float)fracPart / 49152.0; // Convert into fractional portion of float
fracPart = ((m2 & 0xff) << 8) + (m1 & 0xff); // Reassemble 16-bit value
return ((float)fracPart + floatPart) - 1000.0; // Complete reconstructing original float
}
String[] listFileNames(String dir) { // Return the filenames from a directory as an array of Strings
File file = new File(dir);
if (file.isDirectory()) {
String names[] = file.list();
return names;
} else // It's not a directory
return null;
}
Again, the programming interfaces for Processing and Arduino are very similar, and it's easy to mistake one for the other. In fact, both environments store sketches in separate Sketchbook folders, and sometimes the wrong folder will appear when saving a new sketch. Double check every time. You may have to manually navigate to the correct folder.
Once you've saved this sketch in the Sketchbook folder with a filename, Processing has placed it in a subfolder with the same name. It's good to know where to find this subfolder when importing thermal image datasets. The editor window can quickly open it for you by starting at the menu bar and selecting Sketch>Show sketch folder, where the new file should appear.
So far, so good. There are two more sketches to go.
Page last edited January 20, 2025
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