OIV.Inventor.Fields.SoSFImage3.StartEditing(OIV.Inventor.SbVec3i32@, System.Int32@, OIV.Inventor.Fields.SoSFImage.DataTypes@) returns the size of the image in the size and nc arguments; writing past the end of the array returned is a good way to cause hard-to-find core dumps.

Doing a start/finishEditing is the same as doing a call to setSubValues on the whole texture. The getSubTexture will return one more updated regions when called after finishEditing.

Avoid copying the values in/out, if you are just changing the bytes and not changing the dimensions of the image.Using OIV.Inventor.Fields.SoSFImage3.StartEditing(OIV.Inventor.SbVec3i32@, System.Int32@, OIV.Inventor.Fields.SoSFImage.DataTypes@) allows subtexturing, which is a more efficient way of doing texture modification.

Reference