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I wanted to take a photo of some items I'd turned on a lathe, and lined them up. Photo was taken with an older samsung android phone, so absolutely nothing fancy. There are no filters enabled, the only difference between these two photos is the flash.

Why did the flash make the brass look dead grey, and the other parts have a vaguely rose tint ? I expected the brass to pop more with added light.

These are two separate photos taken 8 seconds apart. There are some fluorescent tubes in the room, and an LED tool lamp is to the upper right out of shot. The only lighting change was enabling the flash.

enter image description here

enter image description here


enter image description here
Settings - the flash was the only setting changed between shots.


As requested - exif data:

 Camera-Specific Properties:       
 Equipment Make: samsung                
 Camera Model: SAMSUNG-SM-G870A       
 Camera Software: G870AUCU1BOC5      
 Maximum Lens Aperture: f/2.2   
 Sensing Method: One-Chip Color Area
 Focal Length (35mm Equiv): 31 mm 

Coloured photo----------------------------Grey Photo (where different)

 Image Width: 5312   
 Image Height: 2988   
 Image Orientation: Bottom, Right-Hand 
 Horizontal Resolution: 72 dpi    
 Vertical Resolution: 72 dpi    
 Image Created: 2021:01:24 17:00:10       | Image Created: 2021:01:24 17:00:18
 Exposure Time: 1/33 sec                  | Exposure Time: 1/100 sec
 F-Number: f/2.2                          
 Exposure Program: Normal Program       
 ISO Speed Rating: 200                    | ISO Speed Rating: 50
 Lens Aperture: f/2.2                     
 Brightness: 1.5 EV                       | Brightness: 4.9 EV
 Exposure Bias: 0 EV             
 Metering Mode: Center Weighted Average    
 Light Source: Unknown                 
 Flash: No Flash                          | Flash: Flash
 Focal Length: 4.80 mm          
 Color Space Information: sRGB   
 Image Width: 5312             
 Image Height: 2988            
 Exposure Mode: Auto          
 White Balance: Auto           
 Scene Capture Type: Standard   
 Unique Image ID: F16QLHF01GB     
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    \$\begingroup\$ The answer should be "white balance"… but there's no way white balance could get from one image to the other. Could you double-check you have no "special effects" on the phone? It really does look like some kind of intentional 'sepia/old fashioned' filter, except it's not actually sepia. The 'silver' & white wall have shifted to red, the 'gold' has shifted to white. The red stripes at the rear have shifted to green & the green on the back wall has gone. That's just not a white balance issue. \$\endgroup\$
    – Tetsujin
    Jan 30, 2021 at 9:25
  • \$\begingroup\$ @Tetsujin thank you - I never even noticed that the red handles had changed significantly too. Initially I wondered if brass somehow photographs poorly, but its more than that. The table underneath is cast iron and is part of a pillar drill, it was a convenient height and clear space. Perhaps that was acting as some kind of diffuse reflector too, overpowering ... something ? \$\endgroup\$
    – Criggie
    Jan 30, 2021 at 11:02
  • \$\begingroup\$ Is there anything slightly obscuring the flash, perhaps some grease or other shop liquid? Anything that might have caused the color of the flash's light to be reddish? \$\endgroup\$
    – scottbb
    Jan 30, 2021 at 16:34
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    \$\begingroup\$ Doubtful. The light reflections and falloff look exactly like you'd expect from a small flash such as from a phone. If your finger were partially obscuring, one side would probably be darker. \$\endgroup\$
    – scottbb
    Jan 30, 2021 at 23:03
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    \$\begingroup\$ A test: take the same two photos, but fix the white balance, don't leave it on auto (as you're going from tungsten to flash, perhaps daylight or cloudy would give us the best test.) Make sure to get those red & green bits in the background too, if you can - they seem to have a story to tell as to what's happening. \$\endgroup\$
    – Tetsujin
    Jan 31, 2021 at 7:46

5 Answers 5

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My assumption is that the auto white balance took over.

The image, because you took the photo pretty close is dark everywhere except the brass. If the auto white balance is turned on, the warm tint of it was turned into a neutral color, gray.

See if it is the case. Take a test photo with white paper below. The camera will notice this white and use it to balance the white, leaving the brass alone.

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    \$\begingroup\$ Looks like you're right - " White Balance: Auto" is in the EXIF data. \$\endgroup\$
    – Criggie
    Jan 31, 2021 at 0:05
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    \$\begingroup\$ I'm still not convinced. If it was white balance then you ought to be able to get at least close by adjusting it manually… but you can't. (or I can't, I'd love to see if someone else can). \$\endgroup\$
    – Tetsujin
    Jan 31, 2021 at 11:26
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    \$\begingroup\$ I would expect any not-too-dumb auto white balance to match the CT of the flash whenever the flash is turned on. \$\endgroup\$ Jan 31, 2021 at 13:51
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    \$\begingroup\$ It does seem like auto white balance; I think what happened is that the image was flooded with the light bouncing off of the table, which has an orange-brownish hue (and of course with the light reflected from the brassy objects that are in the center of the image), so the auto white balance got confused and tried to correct for the brassy-orange "illumination". \$\endgroup\$ Jan 31, 2021 at 17:59
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    \$\begingroup\$ On second look - it actually seems like the reds were suppressed specifically (the two red cables(?) in the back have a dark blue-green color) @Criggie: This may sound like a silly question, but, did you by any chance accidentally cover the flash with your finger while taking the photo? Cause that would make the light red-colored, and it would also reduce the range/fidelity of colors that can be captured. \$\endgroup\$ Jan 31, 2021 at 18:10
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This looks like a processor issue. It looks to me like the camera has chosen to use the sepia filter despite the fact that effects are turned off. A white balance error would skew the colors universally. not specifically toward sepia. What camera are you using? It may be time for a replacement.

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  • \$\begingroup\$ As per question, its an older android phone. There is no effect or filter enabled. \$\endgroup\$
    – Criggie
    Jan 30, 2021 at 22:52
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    \$\begingroup\$ Yes, I believe it's a processor issue. The processor is malfunctioning or glitching because the image data overwhelms it. \$\endgroup\$
    – user85781
    Jan 31, 2021 at 2:57
  • \$\begingroup\$ I'm going to go with processor issue here too. What processor? Any of them in the imaging chain. Might have had bad reads, might have debayered the image badly (would need a full res image to check), may have glitched the tables... If it consistently does this, then there's something else going on. \$\endgroup\$
    – J.Hirsch
    Mar 3, 2021 at 20:13
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Well, no EXIF data to go by. The second looks like using a "Sepia" color filter. That would be my first guess, particularly given what happens to color in the rest of the image.

A second guess is that brass is actually highly reflective in the UV and near-UV parts of the color spectrum where the human eye is considerably less sensitive than camera sensors. If we are talking about a typical white LED as illumination, it has kind of a hole in the spectrum between the narrow-band blue color of the actual light-emitting semiconductor and the spread fluorescence spectrum making for the red-yellow-green part of the light emittance. That would make it prone to be less than properly yellow in digital camera pictures under LED lighting or UV-leaning lighting like that of the sun or an actual flash tube without UV filter.

Then there is the problem that a whole lot of lighting is not coming from the flash (check out the highlighted reflections on the round parts: only the reflection pointing straight to the photographer is due to the flash). That means that there is significant light input apart from the flash, and if the white balance is set to "the mobile's version of flash" as white balance setting, the external light source may mess it up. And non-photographic "white" LED lights tend to mix a pulsed narrow-band bluish light source with a semi-continuous yellowish fluorescence. Depending on just what phase you happen to capture, this can also lead to surprising colorings.

But all that fancy hand-waving aside: Sepia filter really looks like what, for whatever reason, happened here. Check the EXIF data of the original photograph.

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  • \$\begingroup\$ Looks like you're right - " White Balance: Auto" is in the EXIF data. There is definitely no filter or effect enabled. \$\endgroup\$
    – Criggie
    Jan 31, 2021 at 0:05
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The first shot is by ambient light. Likely this is warm shop florescent with maybe a mix of standard tungsten bulbs. It is this warm lighting that enhances brass. The second shot is flash. Modern flash outputs a colder light. Actually it simulates north blue sky lighting. You can try setting different color temperature or you could use a image editing software. Another approach is to buy a few inexpensive pin-up lamps with tungsten bulbs. Another approach is a warming filter. These are salmon colored glass or gelation filters that mount or tape over the lens. You want any one of the several color conversion filters. These are amber 85 -- 85B -- 85C buy then off the web.

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LED flash is not white colour (continous spectrum like sun or edison or tungsten bulb). LED is RGB, a mixture of red, green, blue light. Cheaper / older (pseudo-)white LEDs accomplish this by using three separate LEDs (R + G + B). And as others have noticed there is a severe magenta cast in the flash picture which means there is no green in the picture. Could it be that your flash LED is broken / malfunctioning?

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    \$\begingroup\$ but there is green in the picture. The red stripes back left have come out green. There should be no green in them at all (or so slight as to be immaterial) \$\endgroup\$
    – Tetsujin
    Jan 31, 2021 at 16:20

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