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 06/18/2006 03:22:01 PM · #1
I just submitted an image to my first real challenge (had one a long time ago that I submitted without even reading rules, etc), back when I was first starting in photography.

My question:

The max file size is 150KB. I saved my .jpg so that it was 140KB or thereabouts; when i uploaded it to the challenge the image was suddenly like 90KB. Does DPC lower the resolution of the photo you upload? How does the file size change just from uploading the photo? I even went back and checked the original file I uploaded on my hard drive and it still says 140KB.

Whats the deal?

Message edited by author 2006-06-18 15:22:17.
 06/18/2006 05:08:53 PM · #2
hmm...is it that hard of a question? 28 views...no response.
 06/18/2006 05:10:24 PM · #3
I don't know what happened, but DPC didn't do it.
 06/18/2006 05:12:48 PM · #4
I've checked a few of my challenge entries. It doesn't appear that DPC reduces the size. Not sure what happened.
06/18/2006 05:12:49 PM · #5
Did you use Save for Web? It might have have something to do with that.
06/18/2006 05:13:46 PM · #6
im sure there is an php algorithm that resamples the image, coz i saw my photos got desaturated quite a bit when uploaded hence the decreased image size :> ... acutally im very sure in my theory

g
 06/18/2006 05:35:17 PM · #7
Originally posted by gooc:
im sure there is an php algorithm that resamples the image, coz i saw my photos got desaturated quite a bit when uploaded hence the decreased image size :> ... acutally im very sure in my theory

g


More than likely you were editing and saving in a color space other than sRGB (default for web ... or for IE at least). That's a more likely explanation for the desaturation.
 06/18/2006 05:35:30 PM · #8
I'm certain that DPC is not doing anything to your image when you upload it that would affect the size or resolution. It's possible that DPC is counting bits differently than however you're looking at it. Why not do another image, check the size before you upload, upload to your portfolio, and then let's all take a look?
 06/18/2006 06:39:40 PM · #9
DPC definately do not resize or reample your images - this would change the quality of the picture and would influence voting etc - this is why they make you do the resizing etc yourself before upload.

The uploaded size can be a bit smaller - DPC does strip out the text info such as which camera took the image at what settings. I tried it with one of my images (windows reports 128kb, using 132kb on disk, uploaded file is 108kb). If the image was keyworded etc presumably there would have been a bigger difference.

This is why the save for web feature is recommended - it doesn't save this data meaning the file is just the image data - a better quality pic for the same file size.
 06/18/2006 07:53:13 PM · #10
Originally posted by Leok:
DPC definately do not resize or reample your images - this would change the quality of the picture and would influence voting etc - this is why they make you do the resizing etc yourself before upload.

The uploaded size can be a bit smaller - DPC does strip out the text info such as which camera took the image at what settings. I tried it with one of my images (windows reports 128kb, using 132kb on disk, uploaded file is 108kb). If the image was keyworded etc presumably there would have been a bigger difference.

This is why the save for web feature is recommended - it doesn't save this data meaning the file is just the image data - a better quality pic for the same file size.


This is precisely what I was getting at, but didn't quite have the techspeak to put it into coherent sentences. Thanks!
 06/18/2006 10:07:21 PM · #11
This doesn't make sense...there isn't enough "text" in the image file to warrant a reduction from 140kb to 90kb...thats impossible.

The image also desat a little and I did not use the save for web function. The save for web definately desats the picture.

I second the fact that I believe a PHP command is resampling the image. Something is going on during the upload that is changing the file size of the image.

kg
 06/18/2006 10:10:12 PM · #12
Yes...it is in fact doing somethign to my images when I upload them.

I just uploaded this image:



Before the upload it was 101kb...now look at the file size.

06/18/2006 10:17:35 PM · #13
My guess is that there's something funky with the way you're reading out the size prior to upload. I just checked my last four challenge entries. I always carefully size my entries so they're running right up against the 150K limit. My last four entries were all between 141 and 148K. The smaller one had a lot of black background and probably didn't need the full 150K for best res at 72 dpi.

PM me and I'll give you an address to send the quoted file. Let me see how big it really is.

Originally posted by specialk0783:
Yes...it is in fact doing somethign to my images when I upload them.

I just uploaded this image:



Before the upload it was 101kb...now look at the file size.
06/18/2006 10:22:21 PM · #14
so right click on the photo and go to properties tells you a fake file size?

Is that before or after Photoshop tells me the same number on the save as .jpg dialog box?



Message edited by author 2006-06-18 22:22:52.
 06/18/2006 10:38:37 PM · #15
I'm not accusing you of lying or anything, just saying there are other possible explanations than DPC altering your uploaded files. What's wrong with letting somebody else take a look at one of your files?? I just did a test upload, carefully sizing it to 100K with PSCS. Once uploaded, I downloaded it and check and got a reading slightly different (98,790 bytes before, 98,723 after). So DPC apparently shaved .07% of one kilobyte off the file. That's a far cry from your experience. Windows, and other OSs too, often estimate the size in K based on the way drives are partitioned and what the sector size is. Measure your file sizes in bytes before and after and see what YOU get.

Originally posted by specialk0783:
so right click on the photo and go to properties tells you a fake file size?

Is that before or after Photoshop tells me the same number on the save as .jpg dialog box?
06/18/2006 10:56:21 PM · #16
We've actually had a process in place since our first year that optimized any JPG uploaded to remove EXIF and more importantly fix a Photoshop 7 flaw that would cause JPG files saved w/ PS7 to not render in Internet Explorer.

I've removed this optimization for portfolio images, as it is probably unnecessary at this point. I think the optimization may have also removed any embedded thumbnail images, which may account for the drastic file size changes you saw.
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