Quality Loss when Uploading - DPChallenge Forums

09/29/2003 03:13:03 PM · #1

When I save a photo using the Save for Web feature in Photoshop, I can assign a percentage for quality. I often have to make an image smaller to accommodate a better quality photo, so there is give and take.

My question is this: when I save an image at, say 75% quality, it looks very similar in Photoshop to the original image (perhaps more pixelly). When I upload it, however, there seems to be color loss and tonal qualities become less rich.

Is there a way to prevent such color loss before I Save for Web? And am I just dreaming that this is happening?

Thanks!

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/29/2003 03:15:40 PM · #2

Check to see if you are saving it with or without a color profile. I think for most browsers you'll want to use the sRGB profile, but I'm not 100% sure on that. Try uploading two versions and compare on-line. Also, open the files from your local disk with the browser and see what it looks like.

09/29/2003 05:58:40 PM · #3

I'll try that Paul. Any other suggestions? Anyone?

Tamron SP AF 28-75mm f/2.8 XR Di for Nikon

09/29/2003 06:47:28 PM · #4

Have you tried closing the image in Photoshop and re-opening the "save for web" version? It might be related to the JPG compression which I don't believe you will see until you reopen the image.

It's a bit like the argument about working with TIFF or PSD instead of JPG. If you work on an image from beginning to end without re-opening it then you can save it as a JPG many times without hassles. If you were to close and re-open the JPG each time then the quality loss would begin to grow.

Hopefully I've made some sense and gave you something to check. Otherwise, perhaps your gamma settings within Photoshop are different - I used to have a substantial difference between Photoshop and my web browser in terms of how images displayed.

JEM

Sony DSC-F707

09/29/2003 09:00:37 PM · #5

Mark, do I understand correctly that there is no need to Save As a TIFF when you open an image to work on it in Photoshop -- then, of course, Save As a JPEG before it is returned to storage. In other words open as JPEG, work on it and then simply save as JPEG....with no loss of anything?

FranziskaLang

Nikon D100

09/29/2003 09:33:19 PM · #6

Originally posted by sparky_mark:

If you work on an image from beginning to end without re-opening it then you can save it as a JPG many times without hassles. If you were to close and re-open the JPG each time then the quality loss would begin to grow.

Spork99

OM System OM-1

Canon EF 100mm f/2.8 USM Macro

09/29/2003 09:40:02 PM · #7

Originally posted by FranziskaLang:

I actually don't think this is true. Every time you save a jpg file, you loose data, regardless of whether you keep it open or not. It's the action of saving, not of closing and opening that produces the loss.

Originally posted by sparky_mark:
If you work on an image from beginning to end without re-opening it then you can save it as a JPG many times without hassles. If you were to close and re-open the JPG each time then the quality loss would begin to grow.

David Ey

Nikon D80

Nikon AF Micro-Nikkor 60mm f2.8D

09/29/2003 09:40:07 PM · #8

What actions "SAVE" a file? ie:does this happen without our knowledge like so many things in Microsoft stuff?

Originally posted by FranziskaLang:

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/29/2003 10:11:44 PM · #9

With Photoshop, you have to execute the Save or Save As commands. That's why it needs so much free space (about 5 times the size of your file) on the hard drive for the temporary or "scratch" copies.

09/29/2003 11:43:54 PM · #10

So if I save a file only once, it should be pretty okay? This is what I usually do, yet I often see a loss of color saturation and a loss of tone richness when I upload. There is always a balance of getting quality and an image with some size to it, but I have always struggled with "compensating" for the web by adding blacks, darkening, and/or increasing saturation by a few percent.

I'll have to check my gamma settings, whatever they are!

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/30/2003 12:43:02 AM · #11

Can you email me the "good" version in either TIFF or Photoshop format? I'd like to try making the conversion to JPEG and see if you see the same changes.

dwoolridge

09/30/2003 01:40:12 AM · #12

Originally posted by Spazmo99:

If you saved enough times, eventually the image would become unrecognizable.
Originally posted by FranziskaLang:
I actually don't think this is true.
Originally posted by sparky_mark:
If you work on an image from beginning to end without re-opening it then you can save it as a JPG many times without hassles. If you were to close and re-open the JPG each time then the quality loss would begin to grow.

Sparky_mark is correct. From within Photoshop (version 7+), with the current document open, you can save it (write it to a file) as many times as you like, without repeated loss of data. That is, the document's integrity (in memory) is unchanged when you save it. This is easy to test and demonstrate.

Fayech

Nikon D80

Nikon AF Zoom-Nikkor 18-135mm f/3.5- 5.6G ED DX

09/30/2003 01:52:16 AM · #13

i think it is because you are viewing it with your monitors settings versus what the web settings are. i usually save it, then create a little html doc to view the image to see how it would look when uploaded. the lost of quality is from how you can view it at a million colors on your computer, but there are only 250+ colors on the web.

if someone knows how to up the quality, i'd like to know too. :o)

dwoolridge

09/30/2003 02:12:38 AM · #14

Originally posted by dsidwell:

Any other suggestions? Anyone?

I'm assuming you're uploading a 640xN somewhere, like to your portfolio. Place your unadulterated jpeg file somewhere on the net (but not on dpc) publically accessible. Point us to the non-dpc location and the dpc location. It is important that you know the non-dpc version has been untouched by any "magic" (unknown hands).

I have found that DPC will muck around with your upload if it decides to resize it for any reason. I can only assume it isn't touching the print version during upload. As an example,

this uploaded version
can be compared with

the dpc-munged one

The differences in the thumbs are already evident. I uploaded a 640x640 file, but the print preview was resized to 500x500. I can only assume this is when other mysterious conversions were applied too. Strangely, the tiny thumbs were resized without the conversions. DPC may do these conversions when you upload the file, but who knows when or why.

Message edited by author 2003-09-30 02:14:14.

09/30/2003 02:23:16 AM · #15

I agree that it is the act of saving which causes a data loss. However if you remain within Photoshop then it doesn't have to read the version with data loss - so you don't see it on screen. The next time you read from that file you will see the data loss which occured when you saved.

Perhaps I didn't explain it clearly enough. I was trying to imply that without a reload in Photoshop you won't see the loss which occured since the loss occurs during the save, rather than being applied to the image like a filter or resize command.

As someone suggested - you could open a file, click save a hundred times and then save it once as a TIFF with no unavoidable loss in quality. But if you were to open the file again after each save the loss would become quickly apparent.

Originally posted by Spazmo99:

It's the act of saving which causes a loss in the image quality of a jpeg. Each time the file is saved, it is run through a compression algorithm. That algorithm causes some data loss each time it is applied. If you saved enough times, eventually the image would become unrecognizable.
Originally posted by FranziskaLang:
I actually don't think this is true. Every time you save a jpg file, you loose data, regardless of whether you keep it open or not. It's the action of saving, not of closing and opening that produces the loss.

Originally posted by sparky_mark:
If you work on an image from beginning to end without re-opening it then you can save it as a JPG many times without hassles. If you were to close and re-open the JPG each time then the quality loss would begin to grow.

Message edited by author 2003-09-30 02:30:18.

09/30/2003 02:25:17 AM · #16

Originally posted by JEM:

If you never plan to work on the image again there is no need to save a TIFF. When you save as JPEG there is always a data loss - it's a "lossy" file format. If you want to keep the edited image in a lossless format, so that you could do further editing if required then certainly keep a TIFF or Photoshop image.

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/30/2003 02:29:45 AM · #17

Originally posted by Fayech:

This restriction applies to colors defined by HTML code, and does not apply to JPEG images, which can be up to 24-bit RGB (16.7 million colors). If you save a photo in GIF mode, it WILL be converted to Indexed (256) Color. Even then, if you use an adaptive palette, you will retain most of the image's colors.

faidoi

Pentax K10D

Pentax DA 18-55mm f/3.5-5.6 AF

09/30/2003 02:32:13 AM · #18

Do colors differ when you use a Mac and a PC? Brousers?

Canon 12x IS USM (S3 IS built-in Lens) -- 36-432mm (35mm EQ)

09/30/2003 02:36:36 AM · #19

Originally posted by faidoi:

Do colors differ when you use a Mac and a PC? Brousers?

They certainly can.

09/30/2003 02:38:10 AM · #20

Originally posted by faidoi:

Do colors differ when you use a Mac and a PC? Brousers?

Absolutely - everything affects colour. The gamma setting of your PC and/or monitor. The colour temp your monitor is running at. The graphics card and/or computer being used. To a degree even the operating system running. The more you look into colour technology the worse it gets. Color correction of hardware is a science in itself it seems - you can spend hundreds of dollars on hardware and software to calibrate the colour of your monitor.

09/30/2003 11:20:52 AM · #21

Wow. This has been really helpful. I think I'll open my shot in an internet browser to see how it will look; that will give me an idea of...er...how it will look. Oh well.

Very informative discussion!

MWitt