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Participant
August 31, 2021
Answered

Photoshop Levels adjustment

  • August 31, 2021
  • 2 replies
  • 323 views

Hello together. Could anyone tell me the difference between those two parameters shown on the image? Don't they do the same thing? I look forward to your answers.

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Correct answer TheDigitalDog

One stretches the data, one compresses it. 

Input Levels: the tonal range is being expanded. If you had a pixel that was very dark (say 6) and you moved it all the way to the left, it now becomes level zero, black. 

Moving the sliders inward has the effect of increasing contrast. 

Output Levels lets you compress the tonal range into less than the 256 'levels' shown. If you had a pixel that was very bright, say 255 and then moved it to the left, it could be 'grayer' at say 250. 

9.5 times out of ten, if I'm using Levels, it's Input Levels. 

2 replies

TheDigitalDog
TheDigitalDogCorrect answer
Inspiring
August 31, 2021

One stretches the data, one compresses it. 

Input Levels: the tonal range is being expanded. If you had a pixel that was very dark (say 6) and you moved it all the way to the left, it now becomes level zero, black. 

Moving the sliders inward has the effect of increasing contrast. 

Output Levels lets you compress the tonal range into less than the 256 'levels' shown. If you had a pixel that was very bright, say 255 and then moved it to the left, it could be 'grayer' at say 250. 

9.5 times out of ten, if I'm using Levels, it's Input Levels. 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"
D Fosse
Community Expert
Community Expert
August 31, 2021

One is the input slider (top), the other is the output slider (bottom).

 

Just play around with them a bit, and you will see the difference.

Participant
August 31, 2021

I still don't quite understand in which cases what is needed. Could you explain this to me in more details?