sRGB, ppi, printing and other mysteries

[whited3]

So.......after much prodding from SWMBO I've decided that I'd have some of my images printed by a professional lab for display. Easy of course.............I mean, how hard could it be?

Well, too bloody hard so far. I've found another new photography subject I need to learn about

Whinge complete, now I'm asking for help.

The lab wants the colour space to be sRGB with the image at 300 ppi in JPEG format. They say if I provide an image to these spec it'll come out great.

So using CS5:
A) As I always shoot in RAW and start post processing with ACR, I assume I have to set the 16 bit, 300 ppi, sRGB in there first?

B) In CS5 once I've finished editing, I need to save the image as a TIF ensuring I've ticked the "ICC Profile sRGB" box.

C) Then for the image to send to the printer, I resize the image to what I want and save it as a JPEG.

Am I on the right track here folks?

Should I be working in RGB or sRGB during post processing? My read of the CiC tutorial says RGB. If so I need to remember to change the colour space to sRGB for printing?

Thanks in advance,

Mark

[Colin Southern]

Hi Mark,

Sorta / Kinda.

There's really 2 things going on here ...

The first is the colourspace. sRGB is all external labs can handle, for reasons I'm yet to understand. The two easiest ways to get the image in sRGB is (a) set ACR to spit the image out in sRGB to start with (just click the hyperlink at the bottom of the ACR screen, under the photo), or (b) in Photoshop click on EDIT and then CONVERT TO PROFILE (not "assign profile"), and choose sRGB as the destination / target profile (if it isn't already).

The second is the image size - for some reason they always come up with this 300DPI figure (that drives me bonkers). My suggestion is to click on Image -> Image Size, but leave the resample image box UNticked. That way when you plug in the image dimensions you want the image to be, the DPI will simply adjust to "number of pixels wide or high" divided by "width or height of the image" - if it's more than 300 there's little to be gained by reducing it to 300 and throwing away information, and if it's less than 300 then there's nothing you can do about it.

Definately save as a JPEG - quality 10 to 12 will be fine.

Does this help?

[Geoff F]

Have you read this earlier post, Mark?

As Colin said, demanding a resolution of 300 ppi without giving any requirements for image size (in inches or pixels) is meaningless.

For example you could have an image which was 2 x 1 ins at 300 ppi; but you wouldn't be able to print at 12 x 6 ins from it.

Nowadays, I mostly work in sRGB. You may sometimes get slightly better results from Adobe RGB but quite a lot of my photos end up on the internet or burnt to disc for someone else to use. And the chances are that wherever the end up, somebody won't be able to use Adobe RGB.

So working with sRGB saves me the trouble of having to do batch conversions; which all too often, I forget to do anyway.

[whited3]

Thanks Colin & Geoff, much appreciated.