Resizing image to be smaller - thin line appears on the edges

[kristinaplasgard]

Hello! 

I have a question related to resizing images. I have an image (or a photoshop work area) which is 5906  ×  5906 pixels. I go to "image" in the top meny - then "image size" - then I resize this image to be half as big, 2953 x 2953 pixels. 

Then I open a new work area, a new document in photoshop, which is 5906 x 5906 pixels again. 

In this case, my image is a patterns with butterflies and flowers. I place the smaller version of the image (2953x2953 pixels) next to eachother to fill the area and make a pattern. BUT - the problem that appears here, is that when I resized the image to be smaller, a thin line appears around the image. Please see photo for reference. 
Also, when I have only the smaller image open, and I zoom in to around 150%, I can see this "thin line", it is the pixels closest to the edges of the images that have gotten brigther in colour. 
I would be so thankful for help on how to solve this and why it appears. 
(I also opened the original file 5906x5906 pixels in an other standard image programme in Mac and Windows, resized the image to half its size - and no such line appeared!). I could put that smaller version of the image into photoshop and this problem did not exist. But - I dont want to jump between different programs like that. I want to be able to do this in photoshop.
Thank you so much in advance, best wishes from Sweden 🙂 

[Stephen Marsh]

@kristinaplasgard - Flatten a copy of the image before resizing.

Edit: if you need to retain the layers, work in a duped file or at least make the lower layer a Background layer if it extends to all canvas edges (Layer > New > Background from Layer).

[kristinaplasgard]

Hi! Thank you for replying. I am not a fluent english speaker, so I am just trying to understand what you mean 🙂 
When you say "Flatten a copy" - what does that mean? Do you mean that all the layers should be put together to be just one layer? Is that what it means? 
If so, my answer is: yes I have already done that. The file is a JPG file with only one layer that I am re-sizing to half its size. 

When you say "duped file" do you mean a copy / a duplication of my layers? 
Should I make the one layer I have in the JPG file a "background layer" , this thing: Layer-new-background from layer"? I have never done that. 
Thank you so so much for your help I really appriciate it!! 🙂 

[kristinaplasgard]

Hi again! I tried to go to layer - new - create background layer. It doesnt help. As soon as i re-size something from 50x50 cm to 25x25 cm, this thinn line appears around/on the edges on the image. I really dont understand this, I could always make images smaller before. 

[D Fosse]

I can not replicate this on a flattened image (Background, in italics).

However, it does happen when you resize floating layers, which for instance is what you get if you crop with "delete cropped pixels" unchecked. Even if it's a jpeg - it's not a jpeg when it's open, it only becomes a jpeg when you save it.

Resizing floating layers will include empty pixels outside the frame.

Are you sure it's not just a display artifact? It can happen with some GPU/driver combos. I'm not getting that now, but I've seen it in the past. Try to view at 100% or higher even ratios (200, 400 etc).

[c.pfaffenbichler]

I place the smaller version of the image (2953x2953 pixels) next to eachother to fill the area and make a pattern.

Why don’t you create a proper Pattern (Edit > Define Pattern) from the original image and apply that as a Pattern Layer in the larger document? 

[kristinaplasgard]

Hi there! Thank you for answering 🙂
That is because the patter I have working with is 50x50 cm. And once making that a pattern and repeating it 4 times, it makes the size of the whole thing 100x100 cm. But! I need the file to be 50x50 cm. Therefor, I re-size the original pattern to be half the size, 25x25, then i repeat it with this photoshop tool you are refering to on a 50x50 cm. and this thin line appears... because i resized/made the image smaller. 😞

[c.pfaffenbichler]

Hi there! Thank you for answering 🙂
That is because the patter I have working with is 50x50 cm. And once making that a pattern and repeating it 4 times, it makes the size of the whole thing 100x100 cm. But! I need the file to be 50x50 cm. Therefor, I re-size the original pattern to be half the size, 25x25, then i repeat it with this photoshop tool you are refering to on a 50x50 cm. and this thin line appears... because i resized/made the image smaller. 😞

By @kristinaplasgard

@Stephen Marsh already exlained that you are introducing unwanted interpolation effects at the edges when scaling the image as a Layer. 

So you can scale the flat image and define the Pattern from that. 

[kristinaplasgard]

Hi again! Oh sorry didnt see all the images you posted here! this looks interesting! 😄 Do you fill the pattern 25% and that makes it smaller to fit my wish that is should be 50x50cm? I will test this and take a look!

[kristinaplasgard]

@c.pfaffenbichler Thank you thank you thankd you!!! Yay!!! It worked the way you showed me!
this saves me so much time! you have no idea 😄 thank you sooo much 😄 

[c.pfaffenbichler]

@c.pfaffenbichler Thank you thank you thankd you!!! Yay!!! It worked the way you showed me!
this saves me so much time! you have no idea 😄 thank you sooo much 😄 

By @kristinaplasgard

Unfortunately the interpolation method used for transforming Patterns is a bit of a mystery. 

With certain imagery it can create slightly worse results that creating a new Pattern from a scaled image, but rotation is probably the more problematic aspect.