# Std. of Image

This function block computes the standard deviation of pixel values in an image (range 0–255) and displays the result in its interface. It is useful for assessing image contrast, noise level or overall brightness variation.

## 📥 Inputs <a href="#inputs" id="inputs"></a>

`Image Any` This input socket accepts any image (grayscale or color). Provide the image you want analyzed.

## 📤 Outputs <a href="#outputs" id="outputs"></a>

`Standard Deviation` This output socket delivers a single numeric value: the standard deviation of the image pixel values.

## 🕹️ Controls <a href="#controls" id="controls"></a>

This function block has no interactive controls. It updates its displayed value automatically when image input is provided.

## 🎯 Features <a href="#features" id="features"></a>

* Quick numeric feedback on image variability (contrast/noise).
* Live update of displayed value when a new image is provided.
* Works with both grayscale and color images (produces a single summary number).

## 📝 Usage <a href="#usage" id="usage"></a>

1. Connect an image-producing block to the `Image Any` input. Examples: `Camera USB`, `Load Image`, or `Video`.
2. Read the computed value from the `Standard Deviation` output or from the block's on-screen label.
3. Use the value to trigger logic, logging or visualization (for example, warn if image is too uniform or too noisy).

## ⚙️ Evaluation <a href="#evaluation" id="evaluation"></a>

When the scenario runs and an image arrives at the input, the block calculates the standard deviation of pixel intensities and outputs the numeric result while also updating its display.

## 💡 Tips and Tricks <a href="#tips-and-tricks" id="tips-and-tricks"></a>

* For clearer statistics on a specific area, crop first with `Image ROI` or `Image ROI Select` and feed the cropped image to this block.
* To reduce noise impact before measuring, preprocess with `Blur` or `Denoising` and then measure the standard deviation.
* Compare this value with `Mean Value of Image` to better understand image contrast versus overall brightness.
* When analyzing many images or monitoring trends, pipe the output to `Scope` for live plotting or to `Image Logger` / `CSV Export` for recording.
* If image size is large and you only need a quick estimate, downscale with `Image Resizer` before feeding this block to speed up processing.
* Combine with `Image Resolution and Channel Value` or `Non-zero of Image` to add contextual checks (example: ensure image has expected channels or content before trusting the statistic).

## 🛠️ Troubleshooting <a href="#troubleshooting" id="troubleshooting"></a>

* No value appearing: verify that an upstream block is sending a valid image to `Image Any`.
* Unexpectedly low or high value: confirm you are measuring the intended region (use `Image ROI`) and consider preprocessing with `Blur` or `Denoising` to remove sensor noise or compression artifacts.
* Want visual inspection: connect the same image source to `Show Image` to preview the image while checking the statistic.


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