Very High Image Resolution-Any Quality Disadvantage?

[glennda]

Is there any quality disadvantage to using an image with a resolution that is "too high"?.

In other words, if we have an image that is 300 dpi in a brochure, but we want to use it at 25% in another piece, will the quality suffer if we use the 1200 effective dpi image and let it res down at the RIP? Will it look better if we res it down in Photoshop?

I would prefer to sacrifice processing time with a larger image over creating multiple versions of the same image at different sizes. But if the quality is noticeably improved we will have to.

Thanks for your help..

[DCurry]

Yes, there can be disadvantages. One would be that you will lose any sharpening applied to the image. Images are best sharpened at 100% size. If you reduce the image in the layout and thereby raise the effective resolution, you end up shrinking the halos that sharpening introduces.

Another possible problem could be moire patterns or weird artifacts, especially if your images contain fabric with patterns or houses with horizontal siding or bricks.

Best thing to do is test it out for yourself and see if the results are acceptable to you. Different workflows will produce various results, too.

[Stephen Marsh]

Images are best sharpened at 100% size. If you reduce the image in the layout and thereby raise the effective resolution, you end up shrinking the halos that sharpening introduces

Agreed 100%.

Additionally, some (many?) RIPs are set-up to resample down images above a certain resolution threshold - so you will also have interpolation softness thrown in as well as no sharpening (it will look like the image has had a 1px Gaussian blur applied to it).

Another possible problem could be moire patterns or weird artifacts, especially if your images contain fabric with patterns or houses with horizontal siding or bricks.

Agreed again. when it comes to resampling and aliasing artifacts - there can be good and bad ways to resample an image down in resolution/size. One has to pay attention to repeating patterns.

Best thing to do is test it out for yourself and see if the results are acceptable to you. Different workflows will produce various results, too.

Again - Agreed!


Stephen Marsh

[Lukas Engqvist]

I agree with all the above, but in real life some times you will have to go through with it. For example you may have a cover picture which is repated elsewhere in a magazine, you would optimise the image for the cover but most probably consider any blurring of the image as it is scaled down as a marginal issue compared with the risk of having two optimised images that are unsynchronised.

or even worse the image optimised for the scaled down version ending up on the cover and therefore being too low resolution and oversharpened for its size!

(This is the one feature I actually miss with OPI workflow wich optimised and sharpened images as they were sent to print…*I have asked for and will keep asking that sharpening be somthing we can apply in the layout program, allong with dynamic GCR but that is an OT request )

[glennda]

Thank you so much; your responses are very helpful. I have seen that moire effect on images of fabrics.

I think we can probably get away without creating lower resolution images as a general rule with the understanding that there may be exceptions in come cases.

My concern was the same as yours, Lukas. I worry about operators saving over the larger file, or having a large and small image with the same name in two different folders, files getting linked incorrectly, etc.

I love this blog. It's a treasure of good information.

Thanks again.

[gordo]

Keep in mind that workflows are often set up by default by the equipment vendor to resample images to 300 dpi - and many prepress shops are not aware that is so and that they have the option to change the level of resampling or to even allow images to pass through without applying any resampling.
If you can, always check with your suppliers regarding their policy.

best, gordon p

[David Kunkel]

Thank you so much; your responses are very helpful. I have seen that moire effect on images of fabrics.

I think we can probably get away without creating lower resolution images as a general rule with the understanding that there may be exceptions in come cases.

My concern was the same as yours, Lukas. I worry about operators saving over the larger file, or having a large and small image with the same name in two different folders, files getting linked incorrectly, etc.

I love this blog. It's a treasure of good information.

Thanks again.

Doesn't solve all the issues, but placing the large original into a working Photoshop file as a Smart Object and then saving de-rezzed versions from that secondary file would give you some security for the original.

[glennda]

Thank you all again. I will try the smart objects. I will also speak with some of our vendors, but it may be difficult to structure jobs as they relate to the vendors workflow, because we use so many vendors and we aren't usually told which vendor is doing the job, since that aspect goes through purchasing.

Since you mentioned the print vendors, it made the lightbulb go on. I can continue to use the larger file, and ask my vendors to res them down if they think it's appropriate. Then I won't have to worry about the high res file being over-written by the low res, because the low res will never reside on our server!

Our vendors are usually very helpful with things like this. (we're big money clients with many print runs over 1,000,000 pieces).

: ) duh! Thank you for waking me up.

[DCurry]

Since you mentioned the print vendors, it made the lightbulb go on. I can continue to use the larger file, and ask my vendors to res them down if they think it's appropriate. Then I won't have to worry about the high res file being over-written by the low res, because the low res will never reside on our server!

Sure, make it someone else's problem. Hey, maybe they'll even do it for free, or even give you a big discount for allowing them the privilege.

[mattbeals]

Well... If you're looking to optimize images at various sizes then try Elpical Claro for InDesign or Premedia Server with Job Client. Claro will analyze the image size and resolution to find the effective resolution. You can then optimize the image, including sharpening, for each image. Even if you have 5 copies of the same image in the layout. Each one is processed separately. Then Claro will re-link the optimized image. You can do size/resolution only, color only or both. Runs right in InDesign CS3-5 directly or you can send the images over to Premedia Server where the work is done. Once Server is done the images are relinked.