Grain and texture, done properly
Grain is the single fastest way to make a digital image read as film — and the fastest way to make it read as a cheap filter. The difference is entirely in whether the grain behaves like silver in an emulsion or like a noise layer pasted over the top.
Where grain actually comes from
Photographic film carries crystals of silver halide suspended in gelatin. Light converts them, development amplifies them, and what remains is a random distribution of clumps that form the image. Crucially the clumps are physically there in the film, so they are part of the image rather than a layer above it: they scale with the image when you enlarge it, they are affected by exposure, and they clump together rather than distributing evenly. Digital noise, by contrast, is generated per pixel in the sensor and is at its worst where there is least light.
Why grain lives in the midtones
In a negative, deep shadows have received almost no exposure, so few crystals developed and there is little visible structure. Bright highlights are nearly fully developed, so the grain merges into solid density. The midtones — where roughly half the crystals developed — show the most variation and therefore the most visible grain. Getting this distribution right is what separates convincing grain from a uniform layer of static: the sky should be smoother than the face, and a black shadow should be almost clean.
Size, speed and enlargement
Faster films use larger crystals to catch more light, so a 400 stock is grainier than a 100 stock, and a 3200 stock is grainier still. Grain size also depends on how much you enlarge the frame: the same negative shows fine grain in a small print and coarse grain in a poster. This is why grain should be scaled to output size rather than fixed in pixels — grain that looks right on a phone screen will look like sand when the same image is viewed large.
Adding grain without ruining the image
Three rules cover most of it. Keep it monochrome or nearly so — colour grain reads as sensor noise, not film. Apply it before any sharpening, since sharpening a grain layer produces crunchy edges that no film ever had. And use less than feels right: grain that is obvious at a glance is usually twice as strong as it should be. The goal is texture you notice when you look for it, not an effect that announces itself.
Frequently asked questions
Should grain be coloured or black and white?
Almost always monochrome. Real colour film does have grain in each dye layer, but the visible result is far more neutral than the rainbow speckle that colour noise produces. Coloured grain is the fastest way to make a film simulation look digital.
Does grain hide poor image quality?
It masks banding and mild compression artefacts genuinely well, which is why it is used in video mastering. It will not rescue soft focus or heavy noise — adding grain on top of noise gives you both.
How much grain is too much?
If grain is the first thing someone notices about the photograph, it is too much. A useful test is to look at the image at the size it will actually be viewed: grain tuned while zoomed to 100% is almost always overdone.
Should grain automatically increase in low light?
Not in real film — grain amount depends on the stock you chose, not the ambient light. But the sensor noise that already appears in low light combines with grain to feel stronger, which is an expected interaction rather than an unwanted spike.
See it on your own camera. CAMCAM runs the film simulation as a live shader on your phone's camera. Nothing is uploaded — the look is computed on the device, frame by frame.
Open CAMCAM Get it on Google Play