Digital Photographic Practice. Ex 7. Tolerance for Noise.

Noise, if present in an image at least at a low level, will not necessary be obvious to the observer unless he or she is familiar with the objects in the image.


The wall used here as a background has the relatively smooth finish of the roller applied emulsion. Observed casually it appears to be smooth. Closer inspection however will show small irregularities caused by painting process as appear in the ISO100 image. Another observer looking at the wall even at ISO400 and unfamiliar with the objects being viewed, would not necessary realise that noise was present and the 'texture' seen was not the actual surface finish.











I find it difficult to see a great
difference in these 7 images at
 normal viewing size

apart from a slight deterioration
in the definition and colour.
(see the 100% enlargements

below)                                                              ISO 100

 

                                                                        ISO 200.

                                                                        ISO 400.

                                                                       ISO 800.

                                                                      ISO 1600.

                                                                     ISO 2500

                                                                     ISO 3200.

Noise @ 100%

 ISO 100.  Slight texture of  background is well defined.

                   Colour of leaves and petals are well

                   represented.

ISO 800. The background is developing a different

                texture. Colour of leaves is becoming diffused.

ISO 3200.   Background, particularly in the shadow

                    areas has changed colour. Leaf colour

                    has significantly changed. Edges have

                    become blurred.

Conclusion:

Would expect considerable loss of image quality beyond ISO 800.