A multiplier between 0 and 1 makes the image darker, while a multiplier greater than 1 makes the image brighter. Real film has non linear reaction to different wavelengths of light, but in the context of rendered images, we can just multiply the resulting colors by a value as a post effect process (so, you can adjust it without needing to re-render the image with different exposure values!). You can also decrease the exposure time to make a less bright image. This longer exposure time lets more light hit the film, resulting in a brighter image. When using a pinhole camera with film, if you wanted a sharp image that was also bright, you could make this happen by exposing the film to light for a longer period of time. That lets a smaller aperture hole be used, giving a sharper and more impressive result. This is why if you’ve ever seen a pinhole camera exhibit at a museum, they are always in very dark rooms. However, smaller apertures also let in less light so are dimmer. The larger the aperture, the blurrier the image. You can even go deeper and make your own fairly high quality pinhole camera if you want: Īs far as aperture size goes, the smaller the aperture, the sharper the image. Pinhole cameras that give decent results can be made easily, even with simple materials laying around the house ( ). These real world imperfections make it so an individual sensor will get light from more than one direction through the aperture, making it blurrier and out of focus. The size of the hole is larger than a single photon, the thickness of the material is greater than infinitesimally small, and there are also diffraction effects that bend light as it goes through. The image is flipped horizontally and vertically and is also significantly dimmer, but it’s perfectly sharp and in focus.Īs you might imagine, a perfect pinhole camera as described can’t actually exist. When this is true, you have a perfectly sharp image of what’s in front of the camera. The idea is that the aperture is so small that each sensor has light hitting it from only one direction. The light goes through the hole and hits a place on the back of the box called the “sensor plane” where you would have film or digital light sensors. If you don’t yet know path tracing basics enough to generate something like the first image, here are some great introductions:Ī pinhole camera is a box with a small hole – called an aperture – that lets light in. We are going to start off by looking at pinhole cameras – which can in fact have Bokeh too! – and then look at lens cameras. There is also a link to the code at the bottom of the post. This post is meant to explain everything you need to know to go from image 1 to image 2. The first image is rendered using an impossibly perfect pinhole camera (which is what we usually do in roughly real time graphics, in both rasterization and ray based rendering), and the second image is rendered using a simulated lens camera. Let’s say you have a path tracer that can generate an image like this:Īdding depth of field (and bokeh) can make an image that looks like this:
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