The chart is needed to validate that the algorithm works: you need to have known colors in the image, you need a reference. (The chart is the ground truth)
Once the chart is back to its exact color, the image can be considered corrected (at least for this distance, illumination…).
If the algorithm brings the chart back to its true colors at several distances and in various conditions, then it can be applied confidently on images without a chart.
Once the chart is back to its exact color, the image can be considered corrected (at least for this distance, illumination…).
If the algorithm brings the chart back to its true colors at several distances and in various conditions, then it can be applied confidently on images without a chart.