# Image Threshold This function block converts an image into a binary or thresholded grayscale image. Use it to separate foreground from background, enhance contrast for detectors, or prepare images for shape and peak analysis. ## đŸ“Ĩ Inputs (sockets) `Image Any` Provide the input image (color or grayscale) to be thresholded. ## 📤 Outputs (sockets) `Image Gray` The resulting thresholded grayscale image. ## 🕹ī¸ Controls `Threshold Type` Choose the threshold algorithm to apply (standard binary modes or automatic OTSU). `Threshold [Min, Max]` Set the minimum and maximum threshold values using a range slider. (Hidden when OTSU is selected because OTSU chooses the optimal threshold automatically.) ## 🎨 Features * `Multiple Threshold Modes` Includes standard binary, inverse, truncation, to-zero, and OTSU automatic thresholding. * `Range Slider` Easy two-value slider for lower/upper threshold control when using manual modes. * `Automatic Mode` OTSU option hides manual sliders and computes the threshold from the image. ## 📝 Usage Instructions 1. Connect an image-producing block to the `Image Any` input. 2. Select the desired `Threshold Type`. If you select OTSU, the slider will be hidden and thresholding is automatic. 3. If using manual modes, adjust `Threshold [Min, Max]` until you get a clear separation of the features you care about. 4. Use the `Image Gray` output for downstream analysis or visualization. ## 📊 Evaluation When the block runs, it converts the input to grayscale (if needed) and applies the selected threshold method. The processed grayscale image is emitted from the `Image Gray` output for further processing. ## 💡 Tips and Tricks * Preprocess noisy images with `Blur` before thresholding to reduce spurious pixels and get cleaner binary results. * If lighting varies across the scene, try combining `Image Threshold` with `Image ROI Select` to threshold only a relevant area. * For color-based separation, use `HSV Filter` or `RGB Mask` first, then feed the masked result into this block. * When working with very large images, use `Image Resizer` to downscale first to speed up interactive tuning. * Visualize results with `Show Image` while tuning thresholds. For recording examples, send the output to `Image Logger` or `Image Write`. * For line-based analysis after thresholding, connect the output to `Histogram On Line` to detect peaks along a row or column. * To locate objects after thresholding, combine this block with `Find Object` or shape analysis blocks (e.g., contour-related blocks) for robust detection. ## 🛠ī¸ Troubleshooting * No clear foreground/background separation: try smoothing with `Blur` or adjust `Threshold [Min, Max]`. * Too many small blobs after thresholding: increase the minimum threshold or preprocess with `Denoising` / `Blur`. * OTSU mode gives unexpected result: switch to a manual `Threshold [Min, Max]` and tune visually with `Show Image`. * Slider disappears unexpectedly: this is expected when `Threshold Type` is set to OTSU (automatic mode).