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Louis246235052n25
Participant
June 4, 2022
질문

When merging layers, do I need to be at 100% zoom when making the merge?

  • June 4, 2022
  • 1 답변
  • 701 조회

Basically I have read that when viewing a merged image at anything other than 100% zoom it can look different to the pre-merged image. What I want to know is do I need to be at 100% zoom when making the merge or is it just an issue with how the image previews at different magnifications due to how it scales the image or something? Will the image be the same at 100% zoom no matter what magnification I make the merge on?

 

Additionally, for anyone who knows the answer, why does the image loom different exactly at anything other than 100% zoom? I think PS creates downscaled previews for different magnifications, but when you merge does it not have a downscaled preview for the newly merged image or something?

 

Thanks in advance.

이 주제는 답변이 닫혔습니다.

1 답변

TheDigitalDog
TheDigitalDog
Inspiring
June 4, 2022

It is the preview, not the actual merging of the data that can be affected. IOW, you can merge at any zoom and the results are the same. The preview however may appear differently. 

100% (1:1) is one image pixel for one screen pixel. When you zoom OUT, this has to be subsampled down to make it look smaller (zoomed out) and the preview isn't as accurate. You can see this very well if you have moiré whereby you may see moiré zoomed out, not zoomed in as just one example. 

Author “Color Management for Photographers" & "Photoshop CC Color Management/pluralsight"
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    Louis246235052n25작성자
    Participant
    June 4, 2022

    Thanks for the reply, and thanks for clarifying whether it changes the final result. Wondering if you can explain why the preview changes when zoomed out after the merge, as I would have thought it should create the same preview as the data is all the same, just on a different layer. E.g if I'm at 50% zoom and I merge the layers, why does the preview change when all I am doing is merging the layers? Does it resample the image displayed in the preview when you merge the layers and as a result change what it looks like at a given magnification that is below 100%? Sorry if I'm missing something.

    davescm
    Community Expert
    davescmCommunity Expert
    Community Expert
    June 4, 2022

    Ok I think I understand now, based on your answers and the thread you linked, basically adjustment previews are based on the downsampled version currently on screen, thus the adjustments are based on incorrect data, however when you merge the adjustment it applies it based on the correct data thus the adjustments that are applied may be different to what was previewed, as the preview was based on how the adjustments applied to the blended colours of the downsampled image, while when the adjustment is merged it is re-sampled based on the full data, which may lead to a different result (considering how mid tonal adjustments have no effect on pure black and white, but if the colour of the downsampled version had lots of grey pixels, it wouldn't be taking that into consideration when it comes to the preview etc).

     

    Sound about right?


    There is also an aditional factor. At zoom levels of less than 66.7% then the preview is calculated using 8 bits/channel - even if the actual image is 16 bits per channel. At higher zoom levels the full image bit depth is used.

     

    Dave

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