Problem With Red

d4fotografix

I do a little automotive photography and find when I upload an image of a red car, it appears pixelated and/or desaturated. The pixelation is really noticeable where the red color is near a black area. This only happens with this color. I have tried many different methods of reducing file size including different methods of downsampling and tried both .jpg and .png and I don't seem to be able to resolve this issue. Not sure if you can see it on the attached image but I think it's really noticeable near the Viper GTS badge and on the fenders near the wheel wells.

Anyone have any thoughts on this? I'm using Photoshop CS5.

- Jim

Peano

Looks like you're saving at a pretty low quality level. Try at least level 6. Also, make sure you're saving in sRGB. I would embed the profile.

d4fotografix

Peano wrote: »

Looks like you're saving at a pretty low quality level. Try at least level 6. Also, make sure you're saving in sRGB. I would embed the profile.

I'm saving at Level 10 and embedding the sRGB profile. It's the same process I use for all others. That's what's so weird about this.

That is what it looks like from your sample, though. I'm wondering if I'm missing something in one of the dialog settings. I've tried Bicubic and Bicubic Sharper downsampling but get the same thing. I'm still wondering why it does this with this color. I had the same problem with a red GT500 photo.

aj986s

Don't have an answer for you, but just curious if you're initial saves are JPG versus RAW. If JPG, maybe you're losing something in the translation. Also, I've done some car shots myself, usually at the race track, and have noticed sometimes that lots of red in the image can cause weird effects/results if WB is set to automatic.

d4fotografix

Original image is RAW. The layered .PSD is flattened and is converted to JPG just before uploading. I need to check what the white balance was set at. I'm also wondering if it has something to do with the sensor on the 50D, but I'm just grasping at straws at this point.

- Jim

Peano

d4fotografix wrote: »

I'm saving at Level 10 and embedding the sRGB profile.

The image you posted doesn't have a profile embedded. Also, it's only 55K. Hard to see how level 10 would leave a file that size.

d4fotografix

Peano,

I double checked it and your right about the image I posted, but the original image on my hard drive that I uploaded does have the sRGB profile embedded. How is that possible? Is the profile being stripped somehow?

mercphoto

Jim, are you doing a save-for-web from Photoshop, or a Save? I'd use Save.

Peano

d4fotografix wrote: »

Peano,

I double checked it and your right about the image I posted, but the original image on my hard drive that I uploaded does have the sRGB profile embedded. How is that possible? Is the profile being stripped somehow?

Could be. When I post on forums, I generally upload to a third-party host like Imageshack, and link to that in the forum. That's what I did with the image above, and the profile stayed embedded.

What size is the image on your hard drive (in kilobytes) before you upload?

d4fotografix

Peano wrote: »

Could be. When I post on forums, I generally upload to a third-party host like Imageshack, and link to that in the forum. That's what I did with the image above, and the profile stayed embedded.

What size is the image on your hard drive (in kilobytes) before you upload?

It's 623Kb.

Here is the same image linked. Can you tell if the profile is embedded?

d4fotografix

mercphoto wrote: »

Jim, are you doing a save-for-web from Photoshop, or a Save? I'd use Save.

I've tried both.

Peano

d4fotografix wrote: »

It's 623Kb.

Here is the same image linked. Can you tell if the profile is embedded?

I meant the size of the image after you reduce its dimensions for the web.

The image you posted here doesn't have a color profile embedded. And it's only 83K, so it's been compressed quite a bit. Certainly not a level 10 save.

EDIT: When you attach an image, as you did, it compresses it again quite a bit. If you embed it through a third-party host, it won't compress it as much (depending on the host).

I just tested an image that was 175K on my computer. Uploaded to Imageshack and Photobucket, it remained that size. Uploaded here as an attachment, it was compressed to 58K.

mercphoto

Peano wrote: »

I meant the size of the image after you reduce its dimensions for the web.

The image you posted here doesn't have a color profile embedded. And it's only 83K, so it's been compressed quite a bit. Certainly not a level 10 save.

EDIT: When you attach an image, as you did, it compresses it again quite a bit. If you embed it through a third-party host, it won't do that.

That makes sense. His image is being processed and compressed twice, not once.

Peano

mercphoto wrote: »

That makes sense. His image is being processed and compressed twice, not once.

It's not so much the number of compressions as the amount. This is from the forum FAQ:

Attaching an image is subject to some pretty confining limitations on size. You'll have to make sure that your image meets those limits before attaching. When you're embedding, the embed code takes care of the resize for you. It's much easier and preferable to embed. Attaching also applies pretty brutal compression to your images. Use attachments as a last resort.

d4fotografix

Peano wrote: »

I meant the size of the image after you reduce its dimensions for the web.

The image you posted here doesn't have a color profile embedded. And it's only 83K, so it's been compressed quite a bit. Certainly not a level 10 save.

EDIT: When you attach an image, as you did, it compresses it again quite a bit. If you embed it through a third-party host, it won't compress it as much (depending on the host).

I just tested an image that was 175K on my computer. Uploaded to Imageshack and Photobucket, it remained that size. Uploaded here as an attachment, it was compressed to 58K.

That's about what's happening. My original file is 300DPI and is 20Mb+ and was reduced (not cropped) to 1024x730 @72DPI. In the forum if I do a "saveas" I get the highly compressed file at around 84kb. The second one was a link from my FTP site and was not "attached". The image on the FTP site is here and does have an embedded sRGB profile and does not have the pixelation. When you insert an image from your Imageshack or Photobucket link does it keep your profile? What is your workflow to reduce from your high-res file to your upload-ready image? I never reduce to anything but a level 10, but I'll go back and re-check it. Again, it only happens with this color.

Peano

d4fotografix wrote: »

That's about what's happening. My original file is 300DPI and is 20Mb+ and was reduced (not cropped) to 1024x730 @72DPI. In the forum if I do a "saveas" I get the highly compressed file at around 84kb. The second one was a link from my FTP site and was not "attached". The image on the FTP site is here and does have an embedded sRGB profile and does not have the pixelation. When you insert an image from your Imageshack or Photobucket link does it keep your profile? What is your workflow to reduce from your high-res file to your upload-ready image? I never reduce to anything but a level 10, but I'll go back and re-check it. Again, it only happens with this color.

Yes, Imageshack and Photobucket both leave the embedded profile intact. For a high res-file I reduce
size in the Image Size dialog box, then save as a jpeg (via either "save as" or "save for web" -- makes
no difference which). In "save for web" I generally save at 80% quality level. Also I never flatten the
layered file. You don't need to flatten in order to save as a jpeg, and I like to keep the layers for
possible future edits.

In the "Save as" dialog, 10 is actually the highest possible quality level. Levels 11 and 12 are
experimental or theoretical or some such. About all they will do is blow up the file size with no
improvement in quality -- and possibly some loss of quality. For web images it's usually safe to go
down to level 8, which is still considered "high."

Just FYI, dpi (actually, it's ppi) isn't relevant unless you're printing. The numbers that matter in this
case are image dimensions in pixels, and the file size (kilobytes or megabytes).

d4fotografix

Peano wrote: »

Yes, Imageshack and Photobucket both leave the embedded profile intact. For a high res-file I reduce
size in the Image Size dialog box, then save as a jpeg (via either "save as" or "save for web" -- makes
no difference which). In "save for web" I generally save at 80% quality level. Also I never flatten the
layered file. You don't need to flatten in order to save as a jpeg, and I like to keep the layers for
possible future edits.

In the "Save as" dialog, 10 is actually the highest possible quality level. Levels 11 and 12 are
experimental or theoretical or some such. About all they will do is blow up the file size with no
improvement in quality -- and possibly some loss of quality. For web images it's usually safe to go
down to level 8, which is still considered "high."

Just FYI, dpi (actually, it's ppi) isn't relevant unless you're printing. The numbers that matter in this
case are image dimensions in pixels, and the file size (kilobytes or megabytes).

Yes, definitely it's "PPI". What dimensions and resolution are the images you post?

Peano

d4fotografix wrote: »

Yes, definitely it's "PPI". What dimensions and resolution are the images you post?

It just depends on the forum. On some there's a limit of 800 px wide. I generally try to keep to dimensions that will display on most people's screens without having to be reduced.

I don't think about resolution (ppi) unless I'm editing for print. For the web, ppi makes no difference at all.