How to Batch Process Images in ImageJ

April 29, 2026

Running the same processing pipeline on hundreds of images by hand is impractical. ImageJ provides two approaches: the Batch Process tool for simple operations, and macros for anything more complex.

Method 1: Built-In Batch Processor

For straightforward operations like converting formats or applying a single filter:

1. Go to Process → Batch → Macro.
2. Set the Input and Output folders.
3. Choose the output format.
4. Paste your processing steps in the macro text box.
5. Click Process.

This works for single-step operations but has limited flexibility.

Method 2: Macro with a Loop

For multi-step pipelines, write a macro that loops over all files in a directory:

dir = getDirectory("Choose input folder");
outDir = getDirectory("Choose output folder");
list = getFileList(dir);

for (i = 0; i < list.length; i++) {
    if (!endsWith(list[i], ".tif") && !endsWith(list[i], ".png")) continue;

    open(dir + list[i]);

    // Your processing steps here
    run("8-bit");
    run("Gaussian Blur...", "sigma=2");
    setAutoThreshold("Otsu dark");
    run("Convert to Mask");

    saveAs("Tiff", outDir + list[i]);
    close();
}

The if (!endsWith(...)) check skips non-image files. saveAs() writes the result to the output folder.

Collecting Results Across Images

dir = getDirectory("Choose folder");
list = getFileList(dir);
results = dir + "results.csv";
File.saveString("Filename,Mean,Area\n", results);

for (i = 0; i < list.length; i++) {
    if (!endsWith(list[i], ".tif")) continue;
    open(dir + list[i]);
    run("Measure");
    mean = getResult("Mean", nResults - 1);
    area = getResult("Area", nResults - 1);
    File.append(list[i] + "," + mean + "," + area + "\n", results);
    close();
}

Common Problems

• Out of memory: Add run("Collect Garbage"); inside the loop after each close().
• Wrong file types processed: Add endsWith() checks for your specific extensions.
• Results table grows indefinitely: Call run("Clear Results"); at the start of each iteration if you only need per-image stats.