Low light printing issue – advice wanted please

[toasty]

I just had the picture below printed 30” x 12” and there is heavy pixellation (almost 8-bit like) in the dark sky above the buildings.


Hong Kong skyline by Jason Cross, on Flickr

On screen (27in Mac) in Lightroom, there’s very little evidence of this but some banding can be seen if exposure is raised very high.

It probably won’t be noticed from a normal viewing distance but I wondered if there was anything I could have done either in-camera or in post processing to minimise this effect?

I'm assuming it's an issue with the image rather than the printing which was done by Loxley Colour.

Any ideas?

Edited by toasty on Wednesday 22 June 08:41

[toasty]

Simpo Two said:

May be JPG compression coupled with attempting to lift exposure on the sky, which would then reveal the artefacts. Is your monitor calibrated?

Thanks for replying Simpo. The monitor isn't calibrated, it's just a standard 5K Mac screen. Is this important for printing? My old Mac was calibrated as I borrowed the kit from a friend but didn't notice much difference. I'll see if I can borrow again or get my own kit.

Looking at the jpeg image I can make out the bands in the darkness though it's nowhere near as blocky. It's as though the printer went to 50dpi for this area but it's all in shades of dark purple and black and only really noticeable up close under light.

[toasty]

Beggarall said:

How big a file do you have - maybe 30" is stretching it a bit?

It was an 11MB jpeg from a 5D MkIII RAW File. I had another daylight picture printed and it's fine, the issue is in the very dark shading.

[toasty]

Pixel Pusher said:

I'd say Simpo is right. JPEG artifacts.

If you have the RAW file, it would I'm sure be a much better result printing from a 300 dpi tiff file. You could use LZW compression if you are sending it remotely for printing as this is lossless. Then ZIP it to reduce further, again lossless.

Are you printing RGB or CMYK?

30" should be no issue at all.

Thanks PP. I'll try re-exporting as tiff format and see if I can tell the difference.

I'm getting frames made up for the two pictures printed. If the artifacts are noticeable once framed on the wall then I might try for a reprint.

No idea on RGB or CMYK. It was whatever Loxley used.

[toasty]

I looked at the image on screen again last night and at 4:1 there's quite a bit of dark noise in the sky. ISO was at 100 so I didn't expect much. Noise reduction did help a bit but maybe I'm expecting too much from the camera.

Exporting in TIFF produced a larger file but on my monitor I couldn't really see the difference. Loxley only take JPEG so I checked all of my settings to their recommendations and apart from not sharpening for print, they were OK.

I doubt I'll get a reprint but will take on all the advice before getting some more prints done. Cheers all.

[toasty]

Pixel Pusher said:

Lynchie999 said:

K12beano said:

..
But ... Have you tried talking to the printers? A good one like Loxley might help you find the right solution???

Yeh, call them up they should be able to sort it out for you! they were good when i spoke to them on the phone...

http://www.loxleycolour.com/help/Preparation

Thanks, I cross referenced that with my settings last night. Only the sharpen for print option was unchecked.

I'm pretty confident nobody will notice once on the wall but wanted to ensure my prep was all in order.

[toasty]

Thanks for all the input guys, I'm learning a lot going through all the possibilities.

I've now taken a photo of the print and posted a crop of the jpeg I see on the screen compared to a close up of what was printed. The print was on the windowsill which will exaggerate the light (the print looks darker in normal conditions) but shows what I am trying to describe.

In answer to some of the questions, the Flickr photo is lower resolution than what was sent to print. I only have LR6 which came bundled with the camera. I'm considering PS but struggle to justify it at the moment. Colour space was sRGB, AdobeRGB (1998) and ProPhotoRGB are also options.

JPEG


Photo


I'll send an email with the same back to Loxley to see if they can suggest anything.

[toasty]

Loxley are on the case and will pick up the print by courier on Tuesday. I'll send another update once I hear back from them