Photoshops HUGE jpgs?

Greg K's picture

He has: 2,145 posts

Joined: Nov 2003

I hardly use photoshop, so I am asking here....

A new guy at work had the task of taking images of items going on our site, and resizing them down to 122x132 pixels.

He tells me he is done with the first one, I check to make sure it looks good and that he did it right (kept proportions, added white background to fill to proper size). I go to show him how to upload it in dreamweaver. I notice that this 122x132 jpg is actually a 560k file?!?!?!?!?!?!

I'm thinking, ok, he saved it some other format and just gave it a .JPG extention. Go in, nope, it was saved as a JPG. Tried the lowest quality level, still over 500k.

Finally I notice a FILE -> SAVE FOR WEB (or something similiar) oprion. Tell it to save as a jpg. even with best quality, it is under 3k.

So this has me wondering, what the heck is the difference? In every other program I have used, saving as a JPG was saving as a JPG....

Any clues?

It's al working, he just kep doing the save for web thing, but this is just my curiousity of what is going on.

-Greg

They have: 96 posts

Joined: Jul 2005

Its all about RESOLUTION Greg.

Even though the dimensions of the original was 122x132, the files resolution was probally set to 300 DPI (dot per inch) When you choose to save for web, the size is automatically change to 72DPI (internet friendly) thus reducing the size considerbly

This is a photo of my Kitten at 200 DPI. note the size is 120KB

Same photo but reduced to 72 DPI. note the size at 41KB.

BTW his name is Butters and hes a full grown cat now heehee

Its hard to see any differences except downloading from the internet. One of my jobs as a website designer is that I always optimize my files for faster site loading. I hope this helps Greg Smiling

BTW I am a Photoshop fanantic Sticking out tongue

demonhale's picture

He has: 3,278 posts

Joined: May 2005

yep just about it... as lex pointed out, how much dots can you fit inside a 122x132 image is the factor... the more dots, the crisper on resize, but much larger file size

They have: 96 posts

Joined: Jul 2005

Exactly however for Internet use , you visually can't see the difference unless your zooming in. Oh and theres the whole "compression" ordeal but thats another matter. For printing you wanna stay at 200DPI for crisp photos.

Greg K's picture

He has: 2,145 posts

Joined: Nov 2003

Ahh. every other program I have used always treated 1 pixel as one dot. ie. if you had a 120 pixel wide image, it was always 120 pixels wide. (ie. if you have it set for 2inches wide, and and you had it 72dpi, you had 144 pixels wide. If you had it set for 300dpi then it was 600 pixels wide.) so I expected when i gave it a final pixel dimension that was how many it would use.

Myself, for all web images, I set units to be pixels just for this reason. The only thing I use another unit for is printed stuff, which I set it inches and do it in Corel Draw. (and becasue i have a color laser that does 600dpi, boy can that make some huge print files...)

Thank you for the help on that.

-Greg

They have: 96 posts

Joined: Jul 2005

No prob Greg. I hope the info was helpful Smiling

They have: 5,633 posts

Joined: Jan 1970

Photoshp was designed for 2 types of media.
1) Internet
2) Print
If you do "Save As..." it assumes you want print quality or that you will come back to it later. Where "Save for web" takes out all the fine lines for print and replaces them with pixels.

timjpriebe's picture

He has: 2,667 posts

Joined: Dec 2004

Uh, didn't everyone else just say that, bja?

JeevesBond's picture

He has: 3,955 posts

Joined: Jun 2002

Oh ignore Bryan, look at that kitten... Awwwww, bless! Laughing out loud

They have: 5,633 posts

Joined: Jan 1970

Yes, but I made it simple. Smiling

Renegade's picture

He has: 3,022 posts

Joined: Oct 2002

I think it was simple enough bja888, it didn't need to be simplfied any further.

Anyway, any images higher than 72dpi won't really be noticed unless zoomed in or printed out simply because 72dpi is about as high a resolution a screen can output.

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