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

Forum|Forum|3 years ago
June 4, 2022
1 reply
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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.

Windows

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TheDigitalDog

Inspiring

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"

L

Louis246235052n25Author

Participant

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.

TheDigitalDog

Inspiring

The preview can change after merging and depending on the layers and blend modes, been this way for decades.

As to zooming OUT past 1:1, here's a file to view to show how sub sampling affects what you see. Download and open so you can see the entire image and you'll see color banding and morie. Zoom to 100%, gone.

https://www.dropbox.com/s/zlwwpqzmh0w5b7b/PrintRes_130mm_720PPI.tif?dl=0