annedi

Thanks, Marc.

Happy that resizing only affects new images. That's what we need.

What is the benefit from rebuilding System Cache? Is that something which I should be doing occasionally?

QUESTION 1

Regarding:   System > Settings > Posting > General > Images & Videos > Maximum Image dimensions to save

If I set maximum dimensions for uploaded images, then it is shown that: 

• If an image larger than these dimensions is uploaded,
  it will be resized to no bigger than the dimensions
  and the original image will be discarded.

My question is whether setting max image dimension affects images uploaded prior to my setting this restriction? Ideally I would like to apply image dimension restrictions only going forward so that old uploaded images would not be affected.

QUESTION 2

Regarding:  Admin > Dashboard > Support > Tools & Diagnostics > Clear System Caches

What does "clearing system caches" actually do? Are images included in "system caches"?

THANKS in advance -- 🙂

Andrea B.

 ok.

I'm looking at this PHP image function reference. Perhaps it would be useful to someone else who has a photography website. 

https://www.geeksforgeeks.org/php-image-processing-and-gd-functions-complete-reference/

If you need less compression to happen, you can change this in your Admin CP > Files > Image Settings > JPG and WebP Quality.

I already did that !! As reported above I have JPG quality = 100.

I'll retry with ImageMagick. Currently it is not working, so it might need reinstallation with appropriate flags.

1) So nobody knows what PHP/Image function changes the quality?

2) Can the "Image library", GD, or ImageMagick be bypassed? (....probably not, but I'm curious anyway)

I found the files. Gd.php, Image.php. 

Does GD resample the upload? Is there someplace I see what happens in the code?

Understood. 😀

I would think that uploaded files of any type shouldn't change just from uploading? We often upload non-JPG files to share (via downloads) and they never change. Like PDFs or raw photo files like NEFs, TIFFs, ARWs and so forth.

We detected the differences between the original JPG and the website JPG by layering the two files in Photoshop and setting the top layer to Difference. The Diff frame was pushed a bit using Auto-Contrast because the JPG changes can be subtle if the original JPG was saved with high quality. Here is one example showing typical JPG compression changes around edges. I was testing here with a very large ((too large)), high quality file. I'll try to get another more reasonable upload change and post that later.

These JPG changes are not of earth shaking importance, but being a photography website we really would like to know what is happening or how to prevent it.

As mentioned, I do not have any restrictions set on image size for either saving or display.

My website is a photography website. So photo quality is important to us, but naturally there are constraints on what can be achieved. We do ask users to resize their images prior to uploading, but I do not have any restrictions on image size for save or for display set. (We are a very small forum, so if a members forgets to resize  an image we ask them to fix that or we resize it for them.)

I recently tested changes to uploaded JPG files. We are using GD with JPG and WebP Quality = 100. Any uploaded JPG file is altered as compared to the original JPG. The quality of the image is slightly decreased. Why is that? I had thought that setting JPG Quality = 100 would prevent such changes?

OK, I think it has all come together now. I'll summarize so that a solution can be declared.

My website began to have sporadic image JPG upload failures. I couldn't completely correlate upload failures with image dimensions or file size, although upload failure did affect mostly large dimension JPGs. We had no problem with PNG uploads of any size.

We had been using ImageMagick all along. Lowering the ImageMagick quality setting did not fix the problem. Marc suggested switching to GD. That stopped the JPG upload failures. 

Thinking back, I realized that the upload failures began after the change to PHP 8.1.21. Randy suggested that the host might have missed setting some flag/option to ensure ImageMagick ran properly with PHP 8.1.21. So, as Marc suggested, I will ask my host to fix this PHP/ImageMagick incompatibility.

Thanks to SeNior-, Randy, Jim M and Marc for their useful suggestions and help. 😃

My error:  Our host server is running PHP 8.2.8. The forum software, however, is using PHP 8.1.21. I went to look up PHP versions and cited the wrong one above. Pls excuse me! (It was late.)

Anyway, ImageMagick is having problems under PHP 8.1.21 for our website. The switch to GD seems to be working. Shouldn't they both be usable with 8.1.21?

Switching to GD seems to cure the problem. Whew....I really really hope that turns out to be true. But I need to run with GD for a couple of days to be sure. 

Why in the world would ImageMagick "suddenly" start causing problems? Could it have anything to do with upgrading to PHP 8.2.8?

Switching to GD seems to cure the problem. Whew....I really really hope that turns out to be true. But I need to run with GD for a couple of days to be sure. 

Why in the world would ImageMagick "suddenly" start causing problems? Could it have anything to do with upgrading to PHP 8.whatever?

Changing the ImageMagick setting did not help.

Here are some recent upload test results. If there a pattern here, I cannot find it.

JPG, 1400 x 932 px. SUCCESS.
JPG, 1500 x 758 px. SUCCESS.
JPG, 1500 x 1000 px. FAIL.

JPG, 1800 x 1200 px. FAIL.
PNG, 1800 x 1200 px. SUCCESS.

JPG, 2000 x 500 px. SUCCESS
JPG, 500 x 2000. SUCCESS.

JPG, square, 1400 x 1400.  FAIL.
JPG, square, 1800 x 1800. SUCCESS.

Thank you for the suggestion. I have re-set ImageMagick down to 85, and I'll retest with that setting.

I'm not sure, though, why the ImageMagick extension would suddenly start causing problems?

So far there are no upload failures with the Invalid Argument Exception when a PNG image is uploaded. The upload failures only happen with JPG images.

Here are some test results. They seem to be rather random. I am getting upload failures both when image dimension restrictions are in place and when they are not.

Image dimension maximum set to 1200 pixels.
1) Upload 7360 x 4912 JPG. Success. Resized to 1200 px width.
2) Upload 7360 x 4912 JPG. FAIL.
3) Upload 2551 x 2099 JPG. Success. Resized to 1200 px width.
4) Upload 5504 x 5504 JPG. FAIL.

Image dimensions unrestricted.
1) Upload 1400 x 934 JPG. Success.
2) Upload 7360 x 4912 JPG. FAIL.
3) Upload 3680 x 2456 PNG. Success.
4) Upload 1600 x 812 JPG. Success.
5) Upload 1998 x 1416. Success.

We have no 3rd party apps. We do not have CloudFlare.

Yes, perhaps we should set limits on image dimensions and file size, but the fact is that we do not have that restriction in place.

However I have discovered that when the image dimensions are larger than a max 1400 pixels, we get an upload error. Where is that being enforced? In the past we have had successful uploads of images larger than 1400 pix maximum width. It's not making sense to suddenly encounter a restriction on image size. 

Here are our image size settings. No restrictions.

HOWEVER, I could not upload the rabbit image (shown above) until I reduced it to 800 pixels on the long side. Then it finally uploaded OK. Confusion.

I just now was able to induce an image upload_failure. I tried to upload a JPG image from a Bushnell Trail Cam. It was a 2.6MB file with pixel dimensions 1888x1062.

And, as you can see, that image file uploaded quite nicely here. 

So I'm thinking that I have either a server problem (but why I cannot guess) or some kind of configuration problem. I have looked at our settings thru Admin and see that I have no restrictions on size of image uploads. So I'm still baffled why this image uploads here but not on my forum.

Well that's strange! Which line in the quoted system log tells you that, please?

I'll ask the members who experienced the failed upload if somehow the file they tried to upload was empty. Will report back.

Could unusual characters in a filename cause an upload problem? I have warned against this in the past. I tested some uploads of files named like DSC+-#$%.jpg and had no problem. I did not test every possible unusual character.

It was a member's jpg image. I cannot supply that particular image because it did not upload and the member gave up. 

I tried uploading a jpg, jpeg, bmp and gif with no problems. I'm wondering if there was some kind of "traffic" problem at that particular time?

((I've learned so much about running a website from this forum. Nice.))