Very poor quality images

tosca

I'm getting very poor quality images, especially with those shooted at night (see http://www.marie-noelle-augendre.com/photos/galerie/themes/nuit/IMG_4093_01.jpg.php for example), and I'm not sure how to solve the problem.

The images I send to the gallery are all 640px high, or a bit less in case of panoramics. Full image and web-image are the same for me, there is no other way to reach them but the image page.

What I need from ZP to do:
- generate thumbnails for both image and album pages
- add my watermark to full/web-size image

Imagick extension is not available on mutualized servers provided by my hosting service.
All the image qualitiy parameters are set to 100 in the admin.
I tried to get the full image instead of the web-size one, but it doesn't seem to make any difference (currently, it is the full size image that is displayed).

What do you advise so I can display images with a quality rather similar to what I send to the server?

Thanks for hints.

acrylian

What are the image options set to?

If you mean the colors of the images please see the troubleshooting on the user guide.

tosca

No problem with the colors, but with banding/pixelling whatever you name this, as if the image has been too much compressed.

Image options:
- all quality set to 100 (see my first message)
- every other modification unchecked, except for the watermark
- cache as original
- obscure cache filenames enabled
- protect image cache and secure image processor are disabled
- disable hotlinking and cache the full image are enabled
- protected view selected

tosca

Compare the image in Picasaweb: https://picasaweb.google.com/lh/photo/4HyeEy3g0Mnt0XGtUEFYY9uy4YK6BxcBdDj_x5gy75Q?feat=directlink
and Zenphoto: http://www.marie-noelle-augendre.com/photos/galerie/themes/nuit/IMG_4093_01.jpg.php
and see the differences in the sky and ground.

acrylian

Sadly the first link leads to a "not found". So I have no idea how the image should look but the one I see does not really look bad to me.

tosca

Sorry, I thought I'd made it public, I might have forgotten some setting somewhere...

Anyway, I ended up uploading an uncompressed JPEG to the gallery; it's much bigger of course (658Ko) in the beginning but it's only 300Ko after being cached!
And the result is much better too. It might not be necessary for every picture, but I noticed this problem on a couple of others, too, that have also been shooted at night or twilight.

Anyway, I'm still a bit surprised that a quality set to 100 ends up with such reduced a size after watermarking and caching.

sbillard

The GD image library is not too competent, so if you have Imagick available it might do a better job. But really, you should know that it is not a good idea to do multiple re-compression of jpeg files. Jpeg is a loss based compression, so each time you compress the image something gets lost. This often leads to artifacts like you see.

BTW, there is no such thing as an "uncompressed" jpeg. So I presume what you really mean is an un-processed image. Zenphoto does support PNG images, so maybe that would be a better format for you to work with.

acrylian

"uncompressed" jpeg: f you set compression to the highest level (12 in PS oder 100%) ou get a quite uncompressed image not that far away from "print" formats like TIFF actually.

PNGs have another drawback as they seem not to support meta data and of coursre pngs are rather uncompressed and much bigger in size than jpegs. Quite important to consider since especially mobile connections are volume based.

tosca

Unfortunately, Imagick is not an option with my hosting service.

"uncompressed" JPEGs was a wrong expression; I should have said highest quality instead.
Locally, I produce TIFF, which are huge, and support metadata. With my previous gallery, I used to prepare the JPEGs with the biggest size I need and not too much compression so the image will still display fine; the gallery only had to produce the thumbnails for which the display is much less critical.

With Zenphoto, what I was not prepared too is the GD action (what it'll do to my pictures) and the caching (is the original picture in fact never loaded by the visitor?)

I'm still looking for the best way to display the pictures in the gallery. I want them to be seen on screens big enough (certainly no mobile phones), they should be as good looking as possible on the web, with my watermark (I could add it locally before uploading to ZP gallery, but I rather like the idea I can change it whenever I want); of course, the files should not bee too big (especially in the area I live, connections speed are not very high).

Up to now, I didn't have much problem with most pictures, except for those that have some noise problem or have rather big dark areas; for those, I have to pay special attention, and probably upload a JPEG of the highest quality, or even a TIFF?

acrylian

With Zenphoto, what I was not prepared too is the GD action (what it'll do to my pictures) and the caching (is the original picture in fact never loaded by the visitor?)

Not unless you modify your theme to use the full images directly.

I want them to be seen on screens big enough (certainly no mobile phones),

Probably not your decision anymore, if we like it or not the mobile usage is increasing (and soon your refridgerator will be used as well if you believe the tech gurus :-)). There is no "one way" anymore to view a website. And there should not be one "fixed" site as well. Of course that is.

and probably upload a JPEG of the highest quality, or even a TIFF?

The GD libary cannot process TIFFs. But I would always suggest to upload high quality jpegs as the image (all images in our showcase for example are such jpegs) so thumb and other compression stuff does not harm that much. Also make sure they are sRGB profiled.

tosca

Thanks for your answer (by the way, I don't know how to copy part of your message the way you did it, as this forum interface doesn't work the same way others I'm used to).

I agree with you about the mobile usage. Let's say I don't want to make it easy for such viewers as I want my pictures to be seen in big enough formats. And anyway, in the rural area I live - and most of my customers too - people don't use smartphones and tablets like it's been done in cities.

So I'll probably stick to highest quality JPEG, as it appears to work pretty well.

acrylian

The quote I did is just standard html: `

Text

`.

Regarding mobile, sure, each his own, especially if you know your visitors. Though visitors are not limited to your area of course.

tosca

Though visitors are not limited to your area of course.

Of course.
Let's say I'm not very interested in visitors that are not interested enough in my pictures to see them on a mobile phone screen only. :-)
Anyway, CSS hovering effects don't work with touch screens...

I might develop a responsive gallery someday, but it's clearly not my priority.

acrylian

Let's say I'm not very interested in visitors that are not interested enough in my pictures to see them on a mobile phone screen only. :-)

Sure, you can see it that way but it is not really custom friendly, isn't it? ;-) People will do if you like or not. And if they can't they might not come back nowadays… That a wide landscape image does not really "work" on a small screen, granted :-)

Anyway, CSS hovering effects don't work with touch screens…

Not directly at least, on some there is a sort of if you are close on the screen without actually touching. But you always need to define the `active` state of a link additionally to the `hover` one.

tosca

Unfortunately, I need to manage priorities. :-)
I began to work on this Zenphoto gallery... more than one year ago, if I believe my forum joining date, and didn't manage to complete anything publiable until a few days ago.
I'm leaving in a few hours for a couple of weeks, shooting abroad.
When back, I'll have plenty to do, will be on the road more days than I want to think about it, and will not have opportunities to really work on the gallery before several months.
So, this will be 'my' next version... no roadmap yet. ;-)

Right now, I would like the gallery working properly, even if it's for desktops only.
And I'm not sure I understand very well how the cache works...

For example, is there any way to purge only selected image(s) or album(s) from the cache? So I can update the cache only for images I'm replacing?
Links that I've put in pages using tinyZenpage are always broken each time I purge the whole cache. :-(

acrylian

I absolutely understand setting priorities and won't argue with you :-) Just discussion "How it should be at best" :-)

You can clear the cache for a specific album on each albums edit page directly. Or you could just delete the folder within /cache directly.

Regarding tinyZenpage: That is indeed an issue. I opened one: https://github.com/zenphoto/zenphoto/issues/522

tosca

"How it should be at best"

today is getting obsolete quicker and quicker... Who can say what will be the best option in a couple of years? But this is getting more philosophical than technical!

You can clear the cache for a specific album on each albums edit page directly.

Great! I was looking for something like that on the image page, but the album level is fine enough; most of the pictures I use in pages are stored in separate albums anyway.

sbillard

You can also directly delete cached images via FTP.

acrylian

But this is getting more philosophical than technical!

Indeed :-)

tosca

You can also directly delete cached images via FTP.

File names in the cache folders are nothing like the original, and I don't know how to identify a specific image among the others.
So, if I have to delete a whole folder/album, I'd rather do it from the admin screen.

By the way, I don't know if this kind of feature has already been asked for, but I find the navigation through many albums/album levels quite tedious in the admin; wouldn't it be possible to navigate through the whole albums tree with the same kind of combo box that's provided for moving an image?

acrylian

You should open a ticket for that navigation idea. There is a breadcrumb on top of the page as well. And if you don't have too many images you could use your browser tabs to keep the main album page open.

tosca

Done here: https://github.com/zenphoto/zenphoto/issues/523

The breadcrumb is useful when one wants to go back up the same branch, but doesn't allow to go anywhere else in one click.

vincent3569

The GD image library is not too competent, so if you have Imagick available it might do a better job

how can I see if Imagick is enabled on my server and how can I enabled it rather than GD image library ?

acrylian

If that is the case setup will tell about and also you find a checkbox on the options. Besides that via `phpinfo()` you get everything that is installed. We have a button on the admin overview page for that, too.