HiResCovers.net

by **jwshaw89** » Wed Mar 20, 2013 8:12 am

chefjoe wrote:
QUOTE (chefjoe @ Mar 20 2013, 08:20 AM) <{POST_SNAPBACK}>
so as a novice hobbiest I should upload or save at what 10 or 12, what I'm getting here is if a lot of reds are used 11 or 12, but if more blues or darkness lower to 10? What's the bottom line, in the past it was always save at 11 or 12 was best. Size of file really means nothing to me as I have over 900 gb empty, hehe

If you've got the space, may as well go for 12.

But, as Tim says above, you can go as low as 9 with no discernible loss in quality, so long as you only save it the once.

The thread was really me asking why there is such a disparity in file size between setting when the quality is pretty much identical. It makes sense from an upload/download/hosting point of view to have the file at a smaller size if you are able to do so without compromising quality.

by **Bunny Dojo** » Wed Mar 20, 2013 8:04 am

chefjoe wrote:
QUOTE (chefjoe @ Mar 20 2013, 03:20 AM) <{POST_SNAPBACK}>
What's the bottom line, in the past it was always save at 11 or 12 was best.

From as low as 9 to as high as 12, you're great with any way you decide. :cheers:

I'm a fan of 11, but if Kernie likes 9 it's hard to argue with his results.

by **chefjoe** » Wed Mar 20, 2013 7:20 am

so as a novice hobbiest I should upload or save at what 10 or 12, what I'm getting here is if a lot of reds are used 11 or 12, but if more blues or darkness lower to 10? What's the bottom line, in the past it was always save at 11 or 12 was best. Size of file really means nothing to me as I have over 900 gb empty, hehe

by **jwshaw89** » Tue Mar 19, 2013 6:53 pm

Bunny Dojo wrote:
QUOTE (Bunny Dojo @ Mar 19 2013, 07:31 PM) <{POST_SNAPBACK}>
Also, fascinatingly, each time I go to save the file, all of the new information added by the distortion makes the file size larger than if I had saved at quality 12 from the start. So the distortion you're using to decrease file size will actually increase the file size if you should try to re-save the design later. (We're all working from original .psds and such, so this doesn't matter, but it's still kind of interesting. )

[attachment=25121:test.jpg]

That's interesting. I suppose it makes sense insofar as you're inadvertently producing more colour tones (even if only minor variations) each time you save it. A gradient obviously holds more data than a single shade.

Likewise with the repeat saving gradually reducing the quality. If you're only reducing the quality by, for example, 2% each save, then that accumulates over a number of saves until it becomes clearly noticeable from the original.

But as you say, if we're only saving as a .jpg the one time straight from a .psd file, as is almost always the case, then this is of little concern.

Another odd thing is that you can open the image saved at quality 10, do nothing to it, then re-save it at quality 12 and the file size shoots back up to 5mb or so. Surely the absolute best quality you can get is merely a perfect copy of the image you opened? Therefore you'd think the maximum file size should be whatever it was when you opened it. As you're saving at the maximum setting, there should be no colour distortion creating more data. At least not enough to warrant a sudden 2mb increase in size.

It's a bit of a mind bender.

by **Bunny Dojo** » Tue Mar 19, 2013 6:31 pm

jwshaw89 wrote:
QUOTE (jwshaw89 @ Mar 19 2013, 01:59 PM) <{POST_SNAPBACK}>
Of course I would never save as low as 6.

I just went down to 6 because 8 or 10 were still too good-looking to work as examples.

As Kernie mentioned, 12 makes sense when you hope to have something maintained exactly. There are, of course, better alternatives for that kind of thing these days.

But, for one more example, here's a zoomed-in piece of a red canvas saved as a JPEG at quality 9, then opened, re-saved at 9, etc. after 4 generations.

Instead of being a flat (255, 0, 0), it's now (253, 3, 2) and starting to distort at the edges.

Also, fascinatingly, each time I go to save the file, all of the new information added by the distortion makes the file size larger than if I had saved at quality 12 from the start.

So the distortion you're using to decrease file size will actually increase the file size if you should try to re-save the design later.

(We're all working from original .psds and such, so this doesn't matter, but it's still kind of interesting.

)

[attachment=25121:test.jpg]

by **jwshaw89** » Tue Mar 19, 2013 5:59 pm

Bunny Dojo wrote:
QUOTE (Bunny Dojo @ Mar 19 2013, 06:54 PM) <{POST_SNAPBACK}>
I can usually see a slight difference between 10 and 11 but have to agree that the difference between 11 and 12 is very hard to spot at 100% zoom.

It also depends on your image. Grain sharpness, bright colors, and especially the color red are areas where the setting matters. If your image has a lot of pale blues, you won't notice as much loss.

Yeah, I noticed that sharper colours and tones are affected the more you slide down the quality.

Of course I would never save as low as 6. I think 9 is really the threshold, but even only taking it down to 11 reduces the size by over a megabyte.

Many of my own designs have a little grain added to them, which probably allows for more reduction.

by **Kernie** » Tue Mar 19, 2013 5:58 pm

I think the maximum settings are there for instances in which size is not a necessary factor. Even at maximum, JPEG compression is still being applied to the image, and if the image is saved and re-saved with JPEG compression (even at maximum applied) several dozen times, there will begin to be a decline in image quality. Kind of like the old days of VHS and the generation loss that occurs when copies of copies are made. In all my years of experience, however, I have yet to see a decline in quality occur to a JPEG that has been re-compressed countless times, but I'm sure it could occur.

That being said, since we are dealing with a situation in which our covers need to be uploaded to a server and then downloaded by others, file size should be a consideration. Leaving a JPEG at maximum quality for our purposes is unnecessary, as we have said in previous posts.

by **Bunny Dojo** » Tue Mar 19, 2013 5:54 pm

jwshaw89 wrote:
QUOTE (jwshaw89 @ Mar 18 2013, 10:27 PM) <{POST_SNAPBACK}>
However, I notice that changing the setting to '10 maximum' (changing it to 9 results in 'high' rather than 'maximum' quality) reduces the size of the cover to around 2-3mb

I can usually see a slight difference between 10 and 11 but have to agree that the difference between 11 and 12 is very hard to spot at 100% zoom.

It also depends on your image. Grain sharpness, bright colors, and especially the color red are areas where the setting matters. If your image has a lot of pale blues, you won't notice as much loss. For instance, my Psycho custom's photos look pretty much the same, but check out the title:

6 vs. 12

[attachment=25115:6.jpg][attachment=25118:12.jpg]

[attachment=25119:Compare.gif]

by **jwshaw89** » Tue Mar 19, 2013 5:41 pm

kernie82 wrote:
QUOTE (kernie82 @ Mar 19 2013, 06:31 PM) <{POST_SNAPBACK}>
Agreed.

And, technically, something "billboard sized" could withstand even greater drops in quality, possibly even some significant pixellation. Since the intended viewing distance from a billboard is (at minimum) a dozen meters away, the viewer will never get close enough to notice such quality errors. Something that will be seen at close distance, like a blu-ray cover or a magazine spread, should probably maintain a higher level of quality than a billboard.

Indeed, but I meant in terms of dimensions rather than purpose. Like if you were to print a dvd cover at billboard size and scrutinize it as you normally would.

I'm not sure what Photoshop's definition of a 'large file' (which it recommends saving at 12) is, but it certainly isn't a dvd cover.

I simply don't understand where the extra 3mb comes from when saving at 12 as opposed to 9 or 10. If the resolution, dimensions, and indeed quality remain exactly the same (to the naked eye), how can the file be 100% larger? Must be like dead data or something. If that even exists.

I really thought I'd overlooked something because of such a huge discrepancy.

by **Kernie** » Tue Mar 19, 2013 5:31 pm

jwshaw89 wrote:
QUOTE (jwshaw89 @ Mar 19 2013, 11:55 AM) <{POST_SNAPBACK}>
Unless we're talking about printing something billboard sized, I don't think knocking the 'quality' down a few notches makes any difference to printed quality.

Agreed.

And, technically, something "billboard sized" could withstand even greater drops in quality, possibly even some significant pixellation. Since the intended viewing distance from a billboard is (at minimum) a dozen meters away, the viewer will never get close enough to notice such quality errors. Something that will be seen at close distance, like a blu-ray cover or a magazine spread, should probably maintain a higher level of quality than a billboard.

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