Can I blend a long ambient exposure with a flashed shot to improve low-light image quality?
Asked 5/30/2017
3 views
2 answers
0
I need to photograph a dim interior while preserving the naturally present light, but I also want the best possible image quality and enough depth of field. Instead of relying only on very high ISO or a wide aperture, can I make two identical exposures: one longer exposure without flash to capture the ambient light and color, and one shorter exposure with flash to capture cleaner detail and structure, then combine them later in post-processing? Would this produce a usable result?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
1
"Is it possible to take 2 shots, one with a long shutter speed [...] and then an identical shot with low shutter speed and a flash, and combine those afterwards?"
Yes it's possible. What you call frequency separation here would be better achieved with for example a bilateral filter. You can get some inspiration from this paper. Simply put, what it does is to take one shot with a flash and another without, deal with any shadow produced by the flash and use a bilateral filter to combine both images.
"Would the resulting image be any good?"
Good or mediocre will depend on your planned usage of the photo. The paper mentioned above shows some examples of what can be achieved.
Notes:
- don't you may mean that the second shot with the flash is taken with a high(er) shutter speed rather than with "low shutter speed"? [edit: see comments below for discussion on shutter speed and shutter time]
- based on one of your comment of an example use case saying you want to capture a girl in 2 shots, she is is unlikely to remain strictly still during the long exposure and between both shots, unless your workflow is well designed and you and your subject are well prepared.
Originally by user61932. Source · Licensed CC BY-SA 4.0
user61932
8y ago
0
Generated from our catalog & community — verify before relying on it.
Yes — this can work, and it’s a known approach for mixing ambient color with cleaner detail from a flash image. The idea is to take one frame without flash for the scene’s natural light and color, then a second frame with flash (typically at a faster shutter speed) for sharper luminance/detail.
A simple way to think about the blend is: use the ambient shot for color, and the flash shot for luminance/detail. Some editors do this in Lab color mode by taking the a/b color channels from the ambient frame and the L channel from the flash frame. Another approach is blending the images with edge-preserving methods such as a bilateral filter while correcting any flash shadows.
How good the result is depends on the subject and intended use. It works best when the camera is locked down and the scene doesn’t change much between shots. Movement or mismatched flash shadows can make blending harder. It’s not really standard frequency separation, and that may be more complicated than necessary.
If accurate color is important, shooting a color card in the scene with and without flash can help you match the final image more reliably.
Recommended products
UniqueBot
AI9y ago
Your Answer
Related Questions
How can I reduce noise when shooting portraits in very low ambient light without losing a natural look?
How can I improve low-light baby photos on a Nikon Coolpix P510 without flash?
How can TTL flash calculate the correct exposure from a single pre-flash?
How do I use a Canon 580EX II in Av mode without E-TTL on a 5D Mark II?
How can I keep direct flash from overpowering a night scene without lots of trial and error?