Image colors shift when uploaded to photo.net

<p>The following are supposedly the same file:</p>

 

<p>The first is a version of the file coming from my own server:</p>

 

<p><img src="http://64.81.64.200:81/images/outside/ConwaySummit20060527.jpg"></p>

 

<p>The next version is the "larger" version of the file after uploading to photo.net and coming from the

photo.net server.</p>

 

<p><img src="http://d6d2h4gfvy8t8.cloudfront.net/4532037-lg.jpg"></p>

 

<p>The images should be identical since the same file was uploaded to both servers. To my eye there is a

significant change in the quality of the copy uploaded to photo.net, and the result is not flattering to the

image - it seems darker and less saturated and there is some sort of color shift. In particular, the greens

of the photo.net copy look washed out.</p>

 

<p>Comments?</p>

Dan,

 

Are you using a PC or a Mac?

 

And regardless, are you posting to your server in Adobe RBG or sRBG?

 

Photo.net like almost all web applications uses sRGB. I understand MACS are able to unencrypt web images that are posted in Adobe RGB, but that is somewhat beyond my ken, so I cannot write knowledgeably about that.

 

If you have taken an image (or your software converts it to) Adobe RGB, Photo.net's software will convert it to sRGB, the web standard. The gamut (range of colors -- simple explanation) will be considerably changed and there likely would be associated shifts in hue, etc.). I take photos in Adobe RGB primarily because my primary mission (eventually) will be to print.

 

Often I do NOT convert to sRGB when I 'Save to Web' ('save to web is required for Photoshop 7 and above), and there often are color shifts, though with my style of shooting, those shifts frequently are not harmful to the image -- if I were a nature shooter, I would be converting everything before the 'save to web' command.

 

If you are posting sRGB images, then your answer lies elsewhere, and others will have to help you.

 

John (Crosley)

Correction, first line: Adobe RGB and sRGB (Red Green and Blue), -- stated correctly elsewhere in my above post.

 

John (Crosley)

Dan, it must be what John says. In my PC monitor, both images are identical. I am looking at them with Firefox 1.5.

 

So, even if you see a difference in your monitor the rest of the world, or at least PC users (i.e. most of the rest of the world), will see only the non-flattering version. If you care so much about the color quality, try saving your images as sRGB if you plan to upload them.

These pictures look the same to me. They both look a bit flat and dull. Neither has washed out greens- a bit dark maybe and certainly lacking any sparkle. That said I think that despite their origins, I'm getting both pictures from the Photo.net server and so I wouldn't expect them to be different.

 

I do suspect that posting a non sRGB image is the cause of the problem- and I have to say that on the relatively infrequent occasions I post an image here in a thread, its probably hit and miss whether I remember to check and if necessary convert to sRGB and adjust, and then when I look at the image afterwards and may well be disappointed.

More info.

 

My work flow in Photoshop to prepare the image for web use includes converting the

profile to sRGB and then changing to 8 bits, followed by "Save as" to .jpg.

 

I am using a Mac. When I view the image in Apple's Safari browser it looks exactly the

same in Photoshop and in the browser. However, taking the hint from those using other

browsers, I tried the same experiment using the Mac version of Firefox and there both

images look the same - and are darker and less intense than in Safari.

 

My monitor is calibrated and gives me a good indication of what images will look like

when printed.

 

Dan

Dan

 

Conversion to sRGB and spend as much time as you like tweaking it to make it look good.

 

Makes no diff.

 

Comes down to the viewer screen gamma (mac V PC ) and the viewers screen calibration.

 

No point stressing, there is no standard here. What you see on your monitor has no relevance to what I see on mine.

 

C.

Well! Since I am now viewing both of the photos from the PN server, it is little surprise there is no difference. When you upload large files, there are quality issues. Try uploading files of the recommended size and see if there is any difference.

The problem is that you are working on a Mac. (I know, you don't consider this a problem, but bear with me.)

 

Except on the Mac, all web browsers ignore the ICC color profiles embedded in TIFF, JPG, PNG, and other image formats. They *assume* that the images are in the sRGB color space, whether or not they are. If there is no color profile in the image, the browser also assumes sRGB. The Save for Web... functionality in Photoshop (and comparable features in other programs) output images converted to sRGB. If you are working on a PC in Photoshop and you are using a different color space than sRGB, when you look at the local image in your own browser, you will immediately see a discrepancy in the colors.

 

On the Mac, it doesn't work this way. First, browsers do support color profiles. So if you were using a different color space than sRGB when you were working on that image on your Mac, and you go to display that image locally in your browser, it will look the same in your browser as it did in Photoshop, because both the browser and Photoshop are heeding the actual color profile in the image. Now when you upload that image to a web server, it will look the same in your browser as it did for you in Photoshop, because your browser will still be paying attention to the actual color profile in the image. However, it will not look like that for anybody else, except another Mac user, because everybody else else (80% of your viewers) treats the image as being in sRGB and it isn't.

 

To make matters more complicated, photo.net strips out color profiles. This is because sometimes color profiles embedded in images cause problems for some browsers. This doesn't make a difference on non-Mac browsers. If the image was in sRGB, most browsers will assume that it is in sRGB without a color profile present, and since this is correct, everything is fine and the same as if the color profile was present. If the image was not in sRGB, the assumption that it was will be wrong, but that assumption would have been made even if the color profile was present. So, stripping out color profiles causes no loss of quality for 80% of browsers.

 

But on the Mac, the color profile is now gone and the browser wants it to be there. The Safari browser assumes that the correct color profile is the device profile of the local monitor. Unless you happened to upload an image with that profile (which you almost certainly didn't), that assumption will be wrong, and the image will look bad on your monitor when viewed from photo.net via Safari.

 

This is good in a way because it will cause you to realize that you've uploaded an image that doesn't look right for 80% of the viewers on photo.net. It is bad for you, though, because I don't think there is a way to tell your Safari browser that images without profiles should be treated as sRGB, even though that is correct, and makes Safari like other browsers. It is nice that Safari tries to support the color profiles, but by assuming that images without profiles are in the color space of the monitor, Safari cancels this benefit out for most normal browsing.

<p>A couple of thoughts/responses:</p>

 

<blockquote>"Comes down to the viewer screen gamma (mac V PC ) and the viewers

screen calibration."</blockquote>

 

<p>I don't think that is quite it, since I'm seeing both images in different quality on one

monitor at the same time. (I do understand about the differences in gamma, etc.)</p>

 

<blockquote>"Well! Since I am now viewing both of the photos from the PN server, it is

little surprise there is no difference. When you upload large files, there are quality issues.

Try uploading files of the recommended size and see if there is any

difference."</blockquote>

 

<p>Actually, you are <b>not</b> seeing both files from the PN server. You can verify by

looking at the html that one is coming from PN but that the other is coming from an

external server of mine. I wrote an html link that inserts a copy of the file from the other

server into the page that comes from PN. Trust me on this... ;-)</p>

 

<p>(BTW, what is the "recommended size?")</p>

 

<p>I'm still perplexed by the answers that reference the need to use the sRGB format. I

am converting the files to sRGB before saving in Photoshop. My work process includes

this:</p>

 

<ol>

<li>prepare the image in photoshop using one of the wider range formats not suitable for

the web. Save as .psd.</li>

<li>Resize the image for posting. Do a bit of special sharpening appropriate for the

resized web image. Convert the file to sRGB. Convert to 8-bit. "Save as..." to .jpg format,

typically at a 7 or 8 quality level in Photoshop.</li>

<li>Upload this converted .jpg to photo.net, and occasionally other servers.</li>

</ol>

 

<p>The part I don't understand is this. If many browsers are assuming sRGB then why

would stripping the sRGB data from the file cause it to look any different in some

browsers? In a browser that doesn't see the sRGB info it should display the same as in a

browser that <i>does</i> see it, since in the latter case it would still be interpreted as

sRGB, right?</p>

 

<p>Thanks,</p>

 

<p>Dan</p>