Which is more efficient ? image creation

habbardone

I have a standard image on a "trust seal" and I want to overlay
the name of the client company so that the image is individualized.

My question is this -

Would it be more efficient to do this once and then load the saved image each time it is requested, or would it be better to generate the image dynamically each time.

My server is already over stretched an my gut feeling is that doing the GD is intensive and I should save the images one and then display them when needed.

What do you think ?
Thanks

Derokorian

If the image is not going to change once created - you could create the image if it doesn't exist and if it does exist use the existing one. This way its only made once and only made the first time its requested.

However if it needs to be more dynamic (say changing once a month, week, day) I would build it on request or keep track of the last update, and if not created since last update (see first option).

bradgrafelman

...or just use HTML and CSS to overlay two unrelated images (or even just image and text) on top of each other.

sneakyimp

If your server's CPU is overloaded, then you should definitely avoid regenerating this image every time. If your server's bandwidth is overloaded, you should try and send some cache headers with these images so that the are requested less frequently.

Brad's suggestion sounds pretty good to me, but relies on the browser to render the composite image which may result in slightly poorer quality. This solution would also have slightly higher bandwidth demands as two images are being downloaded and then combined by the user's browser. I also think you'd have to render the client company's name (the text image) as either GIF or PNG because these are the only formats (AFAIK) that support a transparent background.

Weedpacket

The other issue with bradgrafelman's suggestion is that it doesn't affect the image itself; if the user saves it, it won't have the watermark.

But it's definitely more efficient to do something and save the results once and then reuse the result as often as you like, than it is to do the whole thing over and over and over again.

You don't reinstall your operating system every time you want to use the computer and then reformat the hard drive afterwards, do you?

dalecosp

Weedpacket;10988767 wrote:
You don't reinstall your operating system every time you want to use the computer and then reformat the hard drive afterwards, do you?

Not since, oh, 2001 or so. On Windows 😉

IgglePiggle

And in response to several comments:

1) Sending cache headers will cause a pain in the ring if say for example he/she wants to change methods, i.e. not cache the images. And as an added note: I have had to deal with cache images recently and the majority of browsers ignore this and do what the hell they want.

2) Overlaying the image as noted will not retain the watermark and if a user saves the images they will only get the overlayed image.

3) Generating when required is the best solution.

if(file_exists("whatever.png")) {
// Use image
} else {
// Generate
}

If you need to regenerate the image for whatever reason, simply delete it and the script will regenerate.