It would be very useful to have a new extension in ArcMap that allow the modification of a raster, like arcscan, with a toolbar of painting, keeping the referencing of the image and save the new Raster, with any format, in an easy way, without reclassify the raster. This toolbar could have a edit tool, paint tool, eraser tool and colors palette, for example. Some times we have rasters with distortion of colors, shadows, etc, that could be corrected without loosing its referencing inside the ArcMap and keeping the same resolution, just adding the raster and active the tool.
Marked by Kory Kramer as a Duplicate of Add the ability to edit pixel values in a raster dataset. Please continue voting on that Idea.