Page 1 of 1

Compress Pictures

Posted: Thu Feb 07, 2008 11:33 pm
by Forumadmin
It really is a good idea to compress pictures before uploading them.
Ian Howell downloaded two pictures one of 2MB and one of .9MB. They did not upload correctly and created blank thumbnails.
I downloaded them to my PC and used Microsoft Picture Manager , Pictures , Compress and chose 'for Web Pages' and they compressed down to 22KB; saving disk space, download time and processing time to create the thumbnails.

I hope you agree the loss of quality does not detract from the value of the pictures.

Jowett GalleryTips

Posted: Fri Feb 08, 2008 1:38 am
by Robin Fairservice
When one compresses a picture, the picture's resolution is reduced, so it is not so sharp. As computer screeens, however, use a resolution of 72 pixels per inch, the picture would still look OK. A 6" x 4" picture at a 200 reolution would have a file size of 6x200x4x200 which is 960 kb. At a 72 resolution it would be 6x72x4x72 or 124 kb.

Posted: Fri Feb 08, 2008 10:21 pm
by Keith Andrews
Loading large pics to a web server can cause alsorts of issue
1/The softeware on the web server is going to compress the pic anyway, BUT loading a large pic can and often locks the server up...this can mean rebooting the server software and in exteme cases the server its self.
This means that others trying to accress the web site can find it VERY slow , or not working or just show errors.

Administering a server and /or a web site is very time comsuming, and in the case of Joweet web sites, is done voluntary...
Keith just to do the recent upgrade would have had to put in somewhere between 20 and 60 hrs of very frustraing , head banging work..most likly more towards the 60 hrs...this doesnt include route maintaince...
Do not under estimate the work he puts into the jowett web site.

2/The time it takes to upload large pics espec if the person uploading is on a slow connection can take a long time...this can slow a server for others, and even have it time out.
3/ having large
When one compresses a picture, the picture's resolution is reduced,
Yes...having large files uses a lot of bandwidth, remeber those who admin/run servers pay for this...Also it make web pages very slow to load, and down load pcs
Pic off most web sites are a balance between being able to see the pic clear and fast loading....They are not designed to be used to print out high quality pics for one wall or photo album.

If you want your pic to come out the best for reference, reading etc,
1/open in your editor as keith says above
2/ crop out ALL background that is not needed leving only the subject
3/ resize the with to between 500 and 600 max
4/use File/save as choose jpg in the opitions on the save window choose 18 to 45% save
5/Then upload.

This is just resized

Image

This is cropped, resized then compressed
Image

Posted: Sun Feb 10, 2008 11:47 am
by Forumadmin
On a contrary theme.... please make sure that after you have compressed the pictures they are perfectly legible or the detail is really there and you are not imagining it! The brain is very good at filling in the detail from memory.

Also one function of the Gallery is to capture archive material for all to see and study. These should be uploaded with the best quailty available and using a lossless compression technique (TIFF or PNG). The images can then be reprocessed with optical character recongnition or image enhancement technologies.

Posted: Mon Sep 08, 2008 8:41 am
by Forumadmin
I did some clean-up on Roger Young's and Ian Howell's albums where there were large pictures (1 or 2 MB!) or Bitmap (.bmp) images. These happily reduced to below 100KB and in .jpg form so that the thumbnail displays.

Re: Compress Pictures

Posted: Fri Sep 30, 2011 8:57 pm
by ian Howell
Keith: -

Thanks for ameding my pictures - I was unaware of this problem.

However, it may be because my computer is quite old and I do not have Microsoft Picture Manager that you refer to but I do have a 'Save' function that gives the options of jpeg, tiff or png, so I will try to use one of these in future (if necessary!).