Virtual.ink documentation

If you have ever noticed a small gap or dark stripe in your light-painting result (a place where the trail briefly disappears before continuing), you are not alone, and it is not Virtual.ink's fault. This is a fundamental limitation of how video cameras work, and it affects every video-based light-painting system, regardless of the software.

Why a Photo Does Not Have This Problem

When you take a regular long-exposure photo, the camera opens the shutter and the sensor soaks up light continuously for the entire duration of the exposure: one second, two seconds, five seconds, however long you set it. Your light source paints a smooth, uninterrupted trail across the whole frame because the sensor never stopped collecting light.

Video is completely different. A video camera does not record one long exposure. Instead, it takes dozens of individual pictures every second, one for each frame. At 25 fps, that is 25 separate photos per second. Between each one, the sensor has to reset and get ready for the next frame. That tiny reset moment, even though it lasts only a few milliseconds, is time your light source keeps moving without anyone recording it.

Virtual.ink receives frames from the capture card and stacks them together. But it can only work with what the camera sends. The frames that were never captured during those reset moments simply do not exist, and that is what creates the gap.

This Is How Video Works, Not a Bug

This is not a Virtual.ink bug, a capture card issue, or anything that can be fixed in software. It is a physical property of every video camera. The only way to completely avoid it would be to use a traditional long-exposure photo instead of video. Video light-painting is a creative trade-off: you gain the ability to see your painting build in real time, but you accept that the result will always have some degree of gap.

How to Make the Gap Smaller

The size of the gap depends directly on the shutter speed you set on your camera in video mode. A slower shutter speed means the sensor stays open longer for each frame, leaving less time for the reset window, which means a smaller gap in your result.

• A shutter speed of 1/25 s at 25 fps keeps the sensor open for almost the entire frame, making the gap as small as your camera will allow.
• A shutter speed of 1/50 s (the standard cinematic default) leaves a larger gap, roughly equal to half the frame period.
• Faster shutter speeds make the gap even larger.

For light-painting with Virtual.ink, use 25 fps and set your shutter speed to around 1/25 s. That is the single most effective thing you can do to minimize the gap. See Camera Connection for the full camera setup guide.

Higher frame rates also help. At 50 or 60 fps, each frame period is shorter, so the absolute duration of the reset window is smaller. If your camera and capture card support 50 or 60 fps, that is another good option.

Why Some Gaps Look Much Larger

If your gap looks very wide, not a thin sliver but a noticeable break in the trail, the most common reason is a shutter speed that is too fast. Many cameras default to 1/50 s or faster in video mode, and some auto modes will push it even higher. At 1/100 s or 1/200 s, the sensor is closed for the vast majority of each frame period, and the gap in your light trail will be large and obvious.

Before assuming something is wrong with the setup, check your camera's shutter speed first. Setting it to 1/25 s at 25 fps is usually all it takes to go from a very visible gap to one that is barely noticeable.

If the Gap Is Still Visible in Your Result

Even at the slowest shutter speed, a faint gap will still exist because the sensor always needs some minimum time to reset. That said, the gap is not always visible. When bright light from the surrounding scene or from the light source itself spills into the gap area — for example, a wide, glowing element that overlaps where the trail passes — the gap can be completely hidden by that light bleed. How noticeable the gap is depends a lot on what you are painting and the background conditions.

When it is visible, a few things help:

• Move more slowly: slower moves cover less distance during the gap, making it much harder to see.
• Fix it in post: select the area around the gap in a photo editor and paint or clone across it. On a smooth trail it usually takes less than a minute.

Related Pages

• Camera Connection: hardware setup and capture card recommendations
• Live Setup: frame rate and resolution settings inside the app
• Troubleshooting: recovery tools and log submission