Watermark reduces quality of images drastically

user10 · September 26th, 2006, 01:05 PM

I just installed the latest version of PhotoPOst and I found that when I turn on watermarking, the quality of the images goes way down. I am using Imagemagick and a GIF watermark while uploading JPG images. The watermarking during upload works as expected, except that the quality and size of the file goes way down after watermarking.

A file that uploads at 112k without a watermark uploads at 82k with a watermark and the quality is noticeably worse.

I think the problem is similar to the one in this thread:
Watermarking images problem.....

From that thread, I searched for the code for @imagejpeg from and found it in three different files. I tried changing it in each of the three files from 90 and 80 to 100 and it made no difference in the quality of the uploads after watermarking.

Does anyone have a suggestion of what might cause the watermarking of an image to reduce the quality so much and what I can do to fix it?

Chuck S · September 26th, 2006, 03:07 PM

That thread is not about the photopost pro gallery

In Photopost quality is set in upload options in admin and by default is 70

You have examples to what you mean?

user10 · September 26th, 2006, 03:55 PM

Quote:

Originally Posted by Chuck S

That thread is not about the photopost pro gallery

In Photopost quality is set in upload options in admin and by default is 70

You have examples to what you mean?

Thank you for the reply. I realize that thread is about the other version, but the problem is the same. I tried changing the quality before I posted, but it didn't seem to help either - the final file was the same size with 70 or 80 quality. Is there any other option which could be causing the watermark process to lower the quality of the large image?

Chuck S · September 26th, 2006, 04:52 PM

As I posted please post examples where you think the quality is less. I dont see any issues with quality and watermarking

user10 · September 26th, 2006, 05:46 PM

Quote:

Originally Posted by Chuck S

As I posted please post examples where you think the quality is less. I dont see any issues with quality and watermarking

Per your request, I have sent an email to support with the details and samples.

Chuck S · September 26th, 2006, 06:41 PM

why not post them here?

user10 · September 27th, 2006, 08:48 AM

I have already sent all of the info via email and would rather not post any links to a testing site here in the forum.

Chuck S · September 27th, 2006, 10:12 AM

via email where we dont have any emails

user10 · September 29th, 2006, 12:47 PM

I am still working on this issue.

Let me rephrase this in a more general way to see if that might help in tracking down the problem I am having. Is there a setting (or settings) somewhere in the Photopost Pro script that determine how much the uploaded images are compressed during watermarking?

It seems to me that the problem here is that I am using jpgs that are compressed at level 80 with Photoshop, but when the ImageMagick adds the watermark, it is compressing them more than the original. Is there somewhere in the code where I can adjust how much the large size photos are compressed during watermarking?

I just checked one of the watermarked images in a graphics program and it shows they are compressed to "66" instead of the original "80" that the file was before I uploaded it.

I need to figure out why the script seems to be compressing the jpg files to 66 and change it to compress only to 80.

Michael P · September 29th, 2006, 12:50 PM

Recompressing compressed images will always introduce more noise; you can set the quality setting in your Admin Controls under image settings. All the image code is located in image-inc.php.

user10 · September 29th, 2006, 12:58 PM

Quote:

Originally Posted by Michael P

Recompressing compressed images will always introduce more noise; you can set the quality setting in your Admin Controls under image settings. All the image code is located in image-inc.php.

Thanks for the reply, Michael.

I just noticed something else strange. No matter what I set "Quality setting for resizing/thumbnails?" to, I get the exact same sized uploaded file. If I set it to 10 or 100, I get the same exact size watermarked upload. Should that setting change the size of the watermarked uploaded image?

I will look in image-inc.php to see if I can find anything to change that helps.

My concern is that the watermarked images show 66 compression while the unwatermarked ones show 80 compression. If I upload the exact same file twice, once with watermarking on and once with watermarking off, then download both images and bring them into an image editor, the watermarked image shows level 66 compression and the unwatermarked image shows level 79 compression. It seems that there must be a setting somewhere to adjust that?

Chuck S · September 29th, 2006, 03:26 PM

As Michael stated if the image your uploading or rebuilding is already compressed it can not be compressed anymore etc thus you can not change quality.

As I stated in the helpdesk if your the same gentleman who sent those images to see I saw not a single difference in those 3 photo links

user10 · September 29th, 2006, 04:35 PM

Thanks for the reply.

You should be able to reproduce the problem by doing what I suggested:

1. Compress a JPG in a photo editing program to 80.
2. Upload the image with watermarking on.
3. Download the image and open it in a photo editing program and check the compression level. It should show 66 instead of 80.

Do the same with an image that is uploaded without watermarking - it will show less compression.

The picture links that I sent privately show a lower quality on the smaller image size. That's not just my opinion, it is proven by the fact that the compression level went from 80 to 66 after watermarking.

I would like to figure out how I can make the compression 80 after watermarking instead of 66.

Thank you.

Chuck S · September 29th, 2006, 06:01 PM

I dont compress images in graphics programs ahead of time since the algorithms used are not the same everywhere.

well I did not see any noticable quality but then we are both judging my our eyes

where are you getting this compression numbers from? I would call it hard pressed to make a matter of fact statement like your making especially if your relying on some graphics program for your info.

In image-inc.php try this in bold

Code:

Content visible to verified customers only.

user10 · September 29th, 2006, 06:32 PM

I have finally figured out where the problem lies:

Line 447 in image-inc.php:

Code:

Content visible to verified customers only.

I changed it to this:

Code:

Content visible to verified customers only.

The only difference is this:

Code:

Content visible to verified customers only.

If I add that code, then the large sized watermarked photo will have the same compression level of the variable that I set - in this case "100", but any number will work depending on what compression level is wanted.

The best solution would be for that to be the same "imgquality" variable that other functions use (so it could be set in the admin), but I am not sure how to implement that the best way?

At least I can now hardcode it and make it work.

Chuck S · September 29th, 2006, 07:26 PM

Code:

Content visible to verified customers only.

user10 · September 29th, 2006, 10:43 PM

Thank you!