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DPChallenge Forums >> Administrator Announcements >> Why you shouldn't resample your prints too large..
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Showing posts 1 - 15 of 15, (reverse)
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03/26/2003 10:48:45 AM · #1
We constantly get approval requests that are borderline on quality at the highest sizes, as the photographer is often trying to just squeak past the DPI limit. Here is the part you're forgetting...

You only make money off your final sales. If a buyer gets your print and is unhappy with his print quality, he's allowed to return that print! That means no sale for you. That same buyer, who likely would have just bought your next lowest print size, will now probably not buy again (or at least not of that same print) for quality fears.

The moral of this story is to pay very close attention to the quality of your image if you are resampling it. By resampling too large, you're hurting yourself, the buyer, and the DPCPrints site as a whole.

This has been a public service announcement ;)

Drew
03/26/2003 11:08:27 AM · #2
Drew,
I thought this was what the review process was for?
I, and I assume many others, have no prior experience of preparing photos for print at this level so I'm relying on the review process to help me out.
If you are currently letting these borderline prints through maybe you should think about tightening up on quality and start refusing them. Otherwise, as you say, DPC Prints as a whole will suffer.

I have had one shot refused at the highest resolution, and that's cool - I only want my work to be seen at the highest quality. I have also tried to keep resampling to a minimum and only submitted for the smaller sizes where necessary. However I do still need the review process to screen the quality for me ... at least until I get good at this!

Cheers for the heads up, and don't be scared of getting harsh on the review process.
Paul
03/26/2003 11:13:18 AM · #3
Originally posted by bod:

If you are currently letting these borderline prints through maybe you should think about tightening up on quality and start refusing them.

We evaluate each on a case-by-case basis, and yes, this is exactly what the review process is there to catch. It definitely makes the job much more tiring, though, when we have to put serious thought into each one. Basically, what I'm saying is that if it looks bad, you've gone too far. If you have to ask yourself if it's too bad, it probably is. And just like you said -- use the review process as a learning tool. If we rejected a print size, take a look at what was rejected and try not to do it again. But whatever you do, don't stop sending prints in! ;)

Drew
03/26/2003 11:40:51 AM · #4
I am also relying on your expertise to alert me when I have gone too far. It has been helpful to have you reject a couple of my shots. Now I think I understand what to look for when I resample these. And thanks for the personal notes of encouragement along the way.

I know there are a handfull of charts in the answers area. But I would love to have a chart that shows:
1 to 1.50 = .6667 to 1 = 2720 x 4080 = 16 x 24 = 10 x 15 = min 6.2MB jpg

I am building my own chart as I go, but i think this information is already available somewhere. I would find it a great help.
03/26/2003 12:06:48 PM · #5
Drew,

I have submitted 9 photos from my Oly C3000 camera. I did the exact same upsizing process (used PS in Bicubic, 10% increments) 7 of the photos were fine but I was warned that two of them were borderline. I have never printed anything bigger that 8X10 and I really don't know how to judge what is good and what is not.

How do you judge the quality? Maybe some kind of tutorial with examples would be helpful.

Thanks,
Roger



03/26/2003 12:15:09 PM · #6
Originally posted by rcrawford:

I did the exact same upsizing process (used PS in Bicubic, 10% increments) 7 of the photos were fine but I was warned that two of them were borderline.

This is very often dependent on the elements of your image -- not all pixels are created equal. Some things just resize better than others.

Originally posted by rcrawford:

How do you judge the quality? Maybe some kind of tutorial with examples would be helpful.

We look at a number of things: the amount of pixelation in the image, the size of the pixelation squares, the cleanness and sharpness of lines and elements of the image, etc. Remember that you start with a finite amount of quality, and that quality can only get worse as you resample.

Drew
03/26/2003 12:17:40 PM · #7
I don't usually upsample my images at all (one reason I'm "border/line mad"), but I have taken two recently submitted images up to 200% using IrfanView, and both were approved. Remember too that most of us have yet to see how our file compares with one of the actual prints.

I was a little more concerned with the 150 dpi limit -- I've printed most everything at 300.

I try to restrict upsizing to images without a lot of detail, and which are less likely to suffer degradation as a result of the upsampling process. Otherwise, I'm fine with just offering a smaller prints.

Maybe you can have a check-box on the submission page:
( ) Image has been resampled
so you can easily tell which photos might have to be checked more carefully...
03/26/2003 12:30:34 PM · #8
Originally posted by GeneralE:

I was a little more concerned with the 150 dpi limit -- I've printed most everything at 300.

We did a lot of tests on print quality before coming to this conclusion. If you're worried about it, though, doubling your image size doesn't help ;)

Originally posted by GeneralE:

Maybe you can have a check-box on the submission page:
( ) Image has been resampled
so you can easily tell which photos might have to be checked more carefully...

It's very easy to tell that the borderline/unacceptable images have been resampled. The questions isn't, "Has this image been resampled?" but rather, "Has this image been resampled too much?"

Drew
03/26/2003 12:47:38 PM · #9
I'm not upsampling to try and increase resolution and smaller sizes, just to try and reach the next-larger size. And I am NOT that good at evaluating the things you're checking, so I will welcome your DQ of a print (either at certain sizes or overall) if at all necessary!

Do you have a strong recommendation on technique? I've tried the 5% incremental technique in PS 5 (about eight steps), and also used IrfanView and just hit the "Double" button, and can't really see a problem with either (although they were different images).

Do you guys get any cut at all from the base price, or is all this extra work coming out of the membership fee?
03/26/2003 12:49:16 PM · #10
Well, all my images are resampled. That's the way I get them out of the camera. A downsampled image looses detail in my case. The only reason for downsampling is because uploading an eight mb file isn't fun.
03/26/2003 12:54:08 PM · #11
Downsampling is not the problem. We are mainly talking about problems with trying to enlarge images, for example, to get my <2mp camera to yield an acceptible 16x20 print. When the programs "upsample" they have to create completely new pixels based on values of the surrounding ones, and the result is never as accurate or sharp as it would have been if the pixels could have been captured natively (like in your camera).
03/26/2003 01:35:12 PM · #12
I see that I forgot to mention it, but what I wanted to stress here is that my straight from the cam files are 2832x2128 from a SCCD that could be compared to one that makes 2048x1536. There has been some upsampeling in the camera (to get the 45 degrees SCCD pixel mapping to a regular 0 degrees one). It is clearly visible that this has been done and could be mistaken for an image that is pushed too far, but it actually contains the most detail.
But it doesn't mean that the 2832x2128 is 300dpi 7x9.5 quality, it is actually about 5x7 (a bit more given a optical resolution that comes close to the D7Hi). The danger is that someone gives the OK for a 150dpi 14x18.....
I have always left a note for the reviewer in the comment field.
03/26/2003 03:31:38 PM · #13
Guilty as charged! : ) Now that I am more aware that I have been pushing the limits a little far on some photos I have a question. If a photo was approved up to 16x24 but I have changed my mind and now only want to allow up to the next highest resolution of 10x15 can I simply leave the price blank for the 16x24 size so that that size isn't available to the public? Even though they were approved I am not sure about a couple of prints but I don't necessarily want to delete them and go throught the approval process again.

T
03/26/2003 03:40:29 PM · #14
yes.. .just uncheck the 'available' box on that size...

03/26/2003 04:41:53 PM · #15
Thanks John, that's what I thought and sorry I missed the chat last night. I left the my question and then I went out.

T


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