Minimagick not reducing png filesize instead its increasing - ruby-on-rails

Question

I want to compress my images only when the size is greater than 200kb before uploading them to s3 bucket,In my case images are not connected with any model, I am directly uploading it to s3 using storage as aws
My Uploader is
class CoverImageUploader < CarrierWave::Uploader::Base
# Include RMagick or MiniMagick support:
#include CarrierWave::RMagick
include CarrierWave::MiniMagick
process :compress_image, if: :size_is_large?
# Choose what kind of storage to use for this uploader:
storage :aws
# storage :fog
# Override the directory where uploaded files will be stored.
# This is a sensible default for uploaders that are meant to be mounted:
def initialize(location_id)
#location_id = location_id
end
def store!(*args)
super
#file
end
def store_dir
"uploads/cover-images/#{#location_id}"
end
def compress_image
manipulate! do |img|
img.quality("60")
img
end
end
def size_is_large? picture
image = MiniMagick::Image.new(picture.path)
(image[:size]/1000) > 200
end
end
I am using following code to upload the image
image = MiniMagick::Image.open(https://abc.s3.amazon.com/uploads/image.png)
image_type = image.type.downcase
image_name = "#{location}.#{image_type}"
image_path = Rails.root.join("tmp", image_name)
file = File.open(image_path, 'wb') do |output|
output.write RestClient.get(cover_image["url"])
output.path
end
uploader = CoverImageUploader.new("test123")
s3_path = File.open(file) do |file|
uploaded_image = uploader.store!(file)
uploaded_image.url
end
For jpg and jpeg the above code is working fine but in case of png image, instead of decreasing the size its increasing the image size
My file size was 602 kb in png but it got increased to 1.3 mb after uploading it to s3
I want it to be compressed so the image can load faster on our webpages.
Can anyone please suggest what should I do for png image to be compressed ?