Are Image Filters in popular photo apps dynamic?

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chayandeb
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Are Image Filters in popular photo apps dynamic?

Post by chayandeb »

Are the Image Filters in popular photo apps like Instagram, Snapseed dynamic? To make my question more clear- Do these apps read the image and then apply the filters accordingly or are these filters like a set of fixed steps? E.g. will an Instagram filter change the same parameters by same magnitude in a very bright picture as it does in a very dark picture?
Can someone please help me understand this? Any citation/paper supporting the answer will be super helpful.

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Chayan Deb

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fmw42
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Re: Are Image Filters in popular photo apps dynamic?

Post by fmw42 »

Since they are proprietary, I suspect, the only way to find out is to modify the image for brightness in some other tool such as IM or Photoshop or GIMP and then submit the original and modified images to Instagram or Snapseed and see what happens.

It is certainly possible that they have an autolevel-like feature that stretches the brightness/contrast to full dynamic range before applying other processing filters. But only a test will tell how much affect there is with regard to any autolevel or autotone function that might be included.

chayandeb
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Re: Are Image Filters in popular photo apps dynamic?

Post by chayandeb »

Thank you Fred for your reply.
I did the test you mentioned.
Here's the image I used:
Image

Applied Instagrams's X Pro II on it:
Image

I decreased the brightness of the original picture on PS:
Image

On applying X Pro II on the image with decreased brightness:
Image

Clearly the tones in both the output are very very different. Can we conclusively say that these filters are not static? Can you help me strengthen this claim?
I am new to Image Manipulation space and I am not able to decisively say that these filters are dynamic.

Regards,
Chayan Deb

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fmw42
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Re: Are Image Filters in popular photo apps dynamic?

Post by fmw42 »

In my opinion, there is either no dynamic aspect or if there is there is very little effect. So at least for this filter, it appears static. It does not seem to adjust in any significant way to the lighting.

P.S. Why is your first result smaller than either the input image or the second result?

chayandeb
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Re: Are Image Filters in popular photo apps dynamic?

Post by chayandeb »

:( Okay.
Talking about the tools like Auto Correct or Auto Color, Auto Auto Contrast, it's very much probable that they read the image and then dynamically change the required parameters of the image.

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fmw42
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Re: Are Image Filters in popular photo apps dynamic?

Post by fmw42 »

chayandeb wrote::( Okay.
Talking about the tools like Auto Correct or Auto Color, Auto Auto Contrast, it's very much probable that they read the image and then dynamically change the required parameters of the image.
Yes, the purpose of those types of functions are to try to correct the image to one degree or another to some more pleasing brightness/contast/coloring.

But they generally work only to a certain degree unless very complex algorithms are used. It is hard to make an algorithm that matches what the human eye wants to see.

You can see some examples of those from my scripts at the link below. For example, look at any script that starts with "auto"

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Re: Are Image Filters in popular photo apps dynamic?

Post by chayandeb »

And the size of both the input images is the same. However, the output which Instagram is giving is of 2 different sizes. It's kind of weird.

holden
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Re: Are Image Filters in popular photo apps dynamic?

Post by holden »

There is an interesting addon for Gimp called FIL which does these effects, basically it is a series of macros.

http://registry.gimp.org/node/24639

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