Why Photos Look Grainy

Graininess refers to the presence of small, irregularly shaped speckles that appear in a photographic image. These speckles are usually visible when the image is enlarged or viewed at high resolution. The graininess is caused by the physical properties of the film or paper that was used to capture the photograph.

In traditional film photography, the image is captured on a film strip made of cellulose acetate or cellulose nitrate. Light enters the camera and is focused onto the film, where it is recorded as a pattern of chemical changes. However, because the film is made up of a grid of tiny silver halide crystals, the captured image is not a continuous digital representation as we know it today, but an analog chemical representation. These crystals are not evenly distributed across the film, resulting in variations in the image quality.

When you look at the above photo you are seeing the maximum resolution of the image. Those grains you see are the basic elelments of the photo. It's the chemistry that is composing the photo.

When the film is developed, the silver halide crystals are converted to metallic silver, and this creates the visible image. However, because the crystals are not evenly distributed, the resulting image will contain variations in density, resulting in visible grain. The larger the crystals, the more visible the grain will be in the final image.  High speed film, indicated by an ASA/ISO number, is grainier than lower ASA/ISO film but all film is made up of grain.

Each different film stock has a specific ISO/ASA(American Standards Association) rating, that lets photographers know how sensitive to light the film is. Films with lower ISO such as ISO 50, ISO 100 or ISO 200 are considered “slower” film, these films are less sensitive to light and will require more light to properly expose the image. They are known for having finer grain, more accurate color reproduction and greater dynamic range which means that they can distinguish between shades and tones of a particular color better than a faster film. They are also ideal for landscape and portraiture.

On the other hand, films with higher ISO such as ISO 800, ISO 1600 or ISO 3200 are considered “faster” film. These films are more sensitive to light, so they require less light to properly expose an image. They are more suitable for action and low-light photography and are characterized by having bigger grains and color shifts.

Grain can be reduced by increasing the resolution of the photograph, but it cannot be completely eliminated. This is why older photographs, which were taken on film, often appear grainy compared to photographs taken with digital cameras. With the advancements in computer vision and neural network technology, tools like digmypics' FaceEnhance are able to improve the quality of old photographs, reducing the visibility of grain and increasing the overall resolution of the image, making the memories captured decades ago more vivid and true to life.