Why are some images blurry?

[Gemini23]

Can anyone help?

A dog portrait image loaded on one wordpress installed site displays okay
as at
[goo.gl ]

BUT

when exactly the same image is uploaded to a new installation the dog portrait image looks blurry - and this also happens with several other images (although not all)
as at
[goo.gl ]

[Gemini23]

Problem resolved. Information for any others with this problem... and a possible solution..
it was theme changing the image size.... added a css plugin with custom css and no works fine.