Photography: techniques for the reduction of “Digital Noise”
In today's tutorial we talk about photography. How many times has it happened to take pictures, affect them on the display of the camera and see them in good condition, then download them on the computer and realize the presence of the noise in the picture.
The digital noise present in the photo is the deterioration which can range from small disturbance barely visible, the disturbo “a puntini” very annoying to see how we will see in the next image it shows how the quality of the image may change, changing the ISO.
In this example, a photo taken at 100 ISO will be darker, but the noise will be imperceptible semi-. A 200 ISO the noise becomes clearly visible, a 400 ISO the image loses quality drastically.
Not only help to increase the ISO noise in photographs. Several factors such as a sensor too small, a sensor too hot, a bad software processing and control inside the camera.
But why is that the phenomenon of noise? In fact nothing other than a Sensor fault internal digital camera, defect irresolvable for which there is no solution given the electronic nature Device. The sensor is the compact very small, certainly much smaller than that of reflex or grandi bridge. A sensor receives the light lens, commuta la luce into an electronic signal and transmits the signal amplifying the internal memory. The smaller is the sensor, as amplified will be the signal. For this reason a small sensor will amplify the signal more than one large, and the noise it will be more visible in the pictures taken by a compact (in which the signal is amplified to much) rather than those of a reflex.
However, there are methods to be applied to low-end cameras more or less valid to reduce the noise to photos, some are small steps that we can all take and reduce the training in a mechanical-physical.
- where possible to set a ISO value is very low, helping to stabilize the image with the help of a tripod or using fixed bearings natural: walls, easels, tables, etc..,
- leave off the camera when not in use so as not to heat the sensor. Normally the sensor is more chill and less noise will have on the photos,
- when settings allow it to save your photos in an uncompressed format (eg RAW the TIFF). JPG compression tends to accentuate the noise in photos, especially if the compression software inside the camera is not the best.
Use the editing
Last resort if the latter have not brought the desired results is rely on photo editing. There are several standalone programs or plugins for the major commercial software at affordable prices (from 30 to 40 Euro) remove automatically noise. Today, however, let's talk about G’MIC, a plugin for Gimp reviewed a few months ago which appears as a common plugin, but in reality is a complete photo editing program completo all’interno di Gimp.
Open interface G'MIC we face different menu items, one of which is “Enhancement” (Improvement). The first item on the above menu is “Anisotropic smoothing“, a procedure that date image, blurs parts of the same color and fashion omogeneo, while maintaining the edges. The result is appreciable even leaving the initial settings.
The following photo prey to Flickr presents the rumore, visible especially in the parts where the color is homogeneous.
The same photo after the process is much improved.
Just look at the two pictures to understand the difference immediately. G'MIC as mentioned above is a very useful plugin, installed on any platform because of its license open source. If I have to raise an objection to the developers prefer to have a full version of all the features separately installable da Gimp, and a version containing some of the effects as a plug-. As it is really the impression you install a program to have two different, a po si fa’ confusing.