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Jpeg File Sizes Are Enormous

Forum|Forum|8 years ago
October 14, 2017
3 replies
18683 views

So I'm trying to create image files that I can sell as digital prints to be printed out as posters.

As such, their dimensions are quite large (18" x 24") and the resolution is 300ppi. (Neither of these attributes can be sacrificed).

It seems no matter what I try, the resulting jpegs I save from photoshop are enormous. Anywhere from 11mb to over 40mb. That's video size!

I realize that such large dimensions and high resolution will create images in the MB, but I've purchased many digital print image files with the same dimensions and resolution that weighed in around 3 mb, so I know it can be done.

Here is what I've tried so far:

Flattening/Resterizing/Merging layers
Using 'Save for Web' feature, removing copyright info/meta data
removing thumbnail preview
resetting photoshop settings

Given that these files will be used to print posters, I can't sacrifice the size or the image quality. What else can I do to drastically reduce file size?

I'm using CS6

Thanks in advance!

This topic has been closed for replies.

Correct answer davescm

To add to what the others have said - file size from jpeg compression is image dependant. Some images compress really well, others result in bigger files.

Use Export save for web (Legacy) and adjust the compression slider whilst looking at the image in the preview. Watch the quality in both fine details and smooth gradients such as sky or backgrounds. You will quickly see when compression issues result in unacceptable artifacts.

Dave

davescm

Correct answer

Community Expert

To add to what the others have said - file size from jpeg compression is image dependant. Some images compress really well, others result in bigger files.

Use Export save for web (Legacy) and adjust the compression slider whilst looking at the image in the preview. Watch the quality in both fine details and smooth gradients such as sky or backgrounds. You will quickly see when compression issues result in unacceptable artifacts.

Dave

S

superherobydayAuthor

Known Participant

Hey Dave, thanks for the response. When you say that file size is image dependent, what factors of the image determine the file size? If two different image has identical ppi and dimensions, what further aspects could cause one to be 40mb and the other 3mb?

Also, excuse my newbness, but I don't see any sliders or anything labelled as "compression" in the Save for Web window. Could it be called something else?

Cheers

davescm

Community Expert

Hi

Large plain areas compress much more readily than areas of fine detail. Try it with a few images.

In Export - Save for Web (Legacy) click on the down arrow next to the quality setting quality setting and a slider appears.

Use the "2-Up" view and you can compare the original to the compressed version. If you look at the bottom of the compressed version you will see the estimated file size.

Dave

Derek Cross

Community Expert

You could probably get away with a resolution of between 200 and 250PPI, it would be worth experimenting and with a JPG compression of around 8.

S

superherobydayAuthor

Known Participant

Hey Derek

Most online printing services require that images be at least 300 ppi, so I can't really sacrifice resolution.

Cheers

Derek Cross

Community Expert

I think you'll find the difference in quality to 250PPi from 300PPI will be imperceptible, especially if the poster is to be viewed from a distance. Don't be too precious!

By the way, IMO don't use Save for Web for this purpose, it's been deprecated for good reason. Use Dave As and select JPG from the drop-down format menu.

D Fosse

Community Expert

11 - 40 MB are extremely small file sizes for those pixel dimensions! 7200 x 5400 pixels is quite big. That reduced footprint is only possible through jpeg data compression - which, BTW, I'd be very careful with if I were you. Jpeg compression is lossy, destructive and above all cumulative.

Work in PSD / TIFF, and only save out a jpeg copy at the very end.

And you should just start to get used to file sizes twenty times as big as what you have now.

S

superherobydayAuthor

Known Participant

Thanks for the reply!

The thing is, I have purchased/downloaded multiple digital image files at large dimensions (24x36) with high resolution (300ppi) that are all between 2-5mb.

In fact, on etsy (where I'm planning to sell digital prints) one is not even allowed to upload files larger than 20mb.

And given that these files generally contain multiple images, a file size of <5mb per image seems not only possible, but very common.

D Fosse

Community Expert

First, get used to thinking in terms of pixel dimensions. That's all that matters to Photoshop - print size/resolution is just slapped on afterwards. It's not a property of the file.

7200 x 5400 pixels print out at 18 x 24" - if you set ppi to 300. If you set ppi lower, it prints that much bigger. Pixels per inch.

The thing is, I have purchased/downloaded multiple digital image files at large dimensions (24x36) with high resolution (300ppi) that are all between 2-5mb.

In that case they are jpeg-compressed to within an inch of their lives. Or the resolution is lower.

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