You can add an accurate scale bar to an SEM image without ImageJ by calibrating the image in NotyCalibration, opening it in NotyScale, and adding a scale bar based on that calibration. The process takes only a few minutes if your image already contains a readable reference scale or valid calibration data.
Ready to begin? Open NotyLab and import your SEM image.
Before You Start
You need:
- the original SEM image
- a visible reference scale bar or valid calibration data
- access to NotyCalibration and NotyScale
Do not estimate the scale from magnification alone. If the image has been resized or cropped, verify its calibration before adding a new scale bar.
1. Import the SEM Image
Open NotyCalibration and import the original SEM image.
Use the original file whenever possible. Resizing an image can change the relationship between its pixels and real-world dimensions.
2. Calibrate the Image
Choose the calibration method that best matches your image:
- Auto Detect: for a clear and readable existing scale bar
- Semi-Auto: for noisy images or scale bars surrounded by text
- Manual: draw a line over the known reference and enter its value and unit
Check that the detected or entered unit is correct, such as nm or µm. Then save the calibration and attach it to the image.
3. Add the Scale Bar
Open the calibrated image in NotyScale. Select the attached or saved calibration, then click Add Scale.
Choose a simple, readable value such as:
- 200 nm
- 500 nm
- 1 µm
- 5 µm
Avoid awkward values such as 0.83 µm unless that exact value is scientifically necessary.
4. Adjust the Scale Bar Appearance
Move the scale bar to an area that does not cover important image features. Bottom-left and bottom-right usually work well.
For most SEM figures:
- use white on a dark background and black on a light background
- keep the bar around 15–25% of the image width
- use a clean sans-serif font
- choose Classic for a minimal appearance
- choose Bar when the image background has low contrast
- check readability at the final figure size
Use the same scale bar style across all panels in a paper, thesis, poster, or presentation.
5. Export the Image
Export the finished image as PNG to keep labels and scale-bar edges sharp.
Before using the image, check that:
- the value and unit are correct
- the scale bar is clearly readable
- important image details are not covered
- the image was not resized after calibration
- the exported image matches the required dimensions
Common Problems
The scale bar shows pixels instead of nm or µm
No physical calibration is active. Select an attached calibration or create a new one in NotyCalibration.
The scale bar length looks wrong
Recheck the calibration line, reference value, and unit. Also confirm that the image was not resized after calibration.
The scale bar is difficult to see
Change its color, increase the line width, or use the Bar style with a contrasting background.