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Derrick5ED4
Participant
August 31, 2021
Question

How to prevent pixilation when descaling photos?

  • August 31, 2021
  • 2 replies
  • 555 views

Hello,

There have been several posts on this, however none of them have ultimately helped me. First, I am about 1 day old in photoshop but have goals to learn how to composite photos. My problem comes when I am trying to combine photos, for example, I've been trying to create a knight, however, when bringing in picture of chain mail and scaling it down for 1 piece of the arm, the chain mail becomes significantly pixilated. 

 

Here is what I've tried so far. 

I've tried making a smart object.

I've tried reducing the size of the photo in photoshop and exporting it as a JPEG and bringing it back in to photoshop. 

 

I've defaulted to using a 1920X1080 worksheet with 300 PPI. 

I've messed around with reducing and increasing the PPI. What I have found out is that the chain mail will only be "non-pixilated" when its scaled so that the PPI in the area of scale matches in innate resolution of the photo. Anything drastically more or less creates pixilation regardless of PPI. My only solution would be to make sure all my stock photos have the same scale and resolution before compositing, which I feel is really unrealistic. 

 

I've watched lots of videos on compositing and see them scaling images incredibly small with no pixilation. The only thing I can think of is that they were able to have photoshop treat that base image as an object and not a photo, where the rules of the PPI do not exist. I however, do not know how they did it. 

 

An example here is how Benny made a character really small with no pixilation at time mark 11:35.

https://www.youtube.com/watch?v=-tB3khXWRbY&list=PL79tlP6xgfAnIEFc34YqPLm8WjXxLlfDZ&index=2

 

Thank you and forgive the ignorance. 

-Derrick

This topic has been closed for replies.

2 replies

davescm
Community Expert
davescmCommunity Expert
Community Expert
August 31, 2021

Hi

ppi (pixels per inch) is irrelevant until you come to print. It is just a number stored alongside the image and is used by the print driver to calculated the actual physical size on paper. It is also used to calculate the rulers in Photoshop when displaying inches or cm. 1920 ppi (as shown in your screenshot) is never needed.

ppi makes no difference to your on screen image.

 

All that matters is the number of actual pixels in the image i.e. x pixels high by y pixels wide.  If you have sufficient pixels then it will look fine. If you do not then it will look pixellated, particularly when you scale up.  

 

Don't zoom in more than 100% when looking at the image quality or every image will look pixellated. 100% zoom in Photoshop is not related to a physical size but means 1 image pixel maps onto 1 screen pixel. So at 200% one image pixel takes up 2x2 = 4 screen pixels and the individual pixels become visible. at 300% zoom 1 image pixel takes up 3x3=9 screen pixels......etc

 

Dave

    D
    Derrick5ED4Author
    Participant
    August 31, 2021

    In other words, most likely the file size of the example shown was gigantic in order for the character to come out clear when zoomed in upon? How would I determine my file size when compositing photos for 3d edit? 

    davescm
    Community Expert
    davescmCommunity Expert
    Community Expert
    August 31, 2021

    What do you mean by "3D edit"?

    It sounds like you are not using 3D at all and actually doing 2D compositing, which is what is shown in that video. For that create your image in the size at which you will view it, or print it if print is the final destination. For viewing on screen in HD use 1920 x 1080px and for 4K use 3840 x 2160px.  For creating images that will be printed, the pixel size depends on the final print size and viewing distance.

    Then add elements as required.

    Very important - start with source images of sufficient pixels, in the elements that you will be using, so that you are scaling them down rather than up. That will always be better than trying to scale up images with too few pixels.

     

    Dave

     

     

      c.pfaffenbichler
      Community Expert
      c.pfaffenbichlerCommunity Expert
      Community Expert
      August 31, 2021

      Could you please post screenshots taken at View > 100% with the pertinent Panels (Toolbar, Layers, Options Bar, …) visible? (One during transformation of a non-Smart Object.) 

      What is the Photoshop > Preferences > General > Image Interpolation setting? 

      D
      Derrick5ED4Author
      Participant
      August 31, 2021

      Certainly. Here is the first ask. As you can see, the only way I was able to reduce pixilation was to siginicantly up the PPI. However then I run in to issues with other photos that aren't the same resolution but I need them at the same scale. 

       

      The setting for Image Interpolation is set to Bicubic Automatic

      Thanks!

       

      c.pfaffenbichler
      Community Expert
      c.pfaffenbichlerCommunity Expert
      Community Expert
      August 31, 2021

      Could you please post a screenshot that displays the problem? 

       

      Ultimately if the rings of the chain-mail are no bigger than one or two pixels across they cannot maintain a clear discernability. 

      That has nothing to do with Photoshop as such but is a basic feature of pixel images. 

      Like if the individual pieces of hair in an eyebrow in a portrait are thinner than one pixel the eyebrow becomes a more or less solid (albeit modulated, noisy, …) area without discernible pieces of hair. 

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