Poster-size 36x24 - blue skies pixellate...

[ClicketyClick]

.. . and I am spending hours using Gaussian blur, the blur tool, the smudge tool etc etc.
There must be a quicker way to assure that the high-res photo you send to the poster-printer guy does not suffer from an unseen pixellation (when I looked at the photo jpeg before I sent it, I didn't notice the aberration that has come out in the 36x24 print). I use a 1920x1200 screen - yet still find it very difficult to tell there is pixellation...? A sky-smoothing technique for large-printing formats...

[kirbinster]

That's only about 50 pixels per inch, you are trying to make a print that is too large from that original. Try 1/2 to 1/3rd the size.

[ClicketyClick]

I size the original in PhotoShop for a 36x24 print (it is in fact scaled-down from the original) at 72dpi... the original is 3231 x 2196 pixels - is that too small for the size of poster I am trying to print? which is why I am getting problems...

[Nicole]

Just for reference, these are the recommended resolutions at AdoramaPix for a poster (24x36"):
Best quality: 7200 x 10800
Minimum required: 2400 x 3600

So I'd say yes, it could be a result of trying to print too big.

[teaking]

I wouldnt scale anything down and I would only pay attention to the pixel numbers being width and height

so at 150dpi print (which is average 300dpi being best) your image would have to be 5400 x 3600 pixels

You say the original image size is 3231 x 2196 if you think you can do a better job of up sizing the image then try that option and re size your image I would recommend one of the bi-cubic methods in photoshop or using fractals if you have it.

Once resized you may need to slightly sharpen the image try a high pass filter it should not sharpen the noise only the lines. By the way for 300dpi print your image needs to be 10800 x 7200 which is a big resize and could cause problems. So think about viewing distance when choosing print resolution as from a few feet away 150dpi is going to look alright.

[ClicketyClick]

Thankyou - the print company omitted any such details before I submitted my Jpeg - (sharp marketing to say the least!) - all they required was a 'high-resolution photograph'.