I decided to take advantage of an online firm for 30% off Canvas prints (Xmas special)
The several images I attempted to upload generated messages saying they were not of a high enough quality for printing. (8" x 10")They were ones I had posted here.
I resize from 2816 x 2112 to 1600 x 1200 before doing any post work for uploading here, and although I do not delete the originals it was the improved resized ones I wanted printed.

Had I upsized again to the original dimensions would here have been any any improvement or degradation?
They looked the same to me, but looks can be deceiving :)

were they jpeg or png? sometimes they have to be in PNG format for canvas

It stated that images must be jpeg :)
Premium quality was only guaranteed up to 6" x 8" at 1200x1600.
They qualified it by saying "If it looks good on your computer and at least fills your computer screen, then we should be able to give you a good print."

pffft! sizing for canvas? you have to use starch!

sorry, couldn't resist...carry on..

LynEve - I am going to take a stab at answering your concern, but I need you to pardon my bluntness in doing so. You mentioned two KEY words: SIZE and QUALITY. Everyone has known since they were teenagers that size and quality matter in PIZZA, PIES, SHIRTS, PANTS, SEX and CREDIT LIMITS. Now thanks to the wizardry of electronics PHOTOGRAPHIC FILES are also included in the list. You are correct in believing that the pixel count is a guide for size, but you forgot that quality is judged by file size or some people call it Resolution. When you resized your photos did you lower your file size by eliminating information? The photos will look the same, but when you merge all the file information to print you get LOW QUALITY. Its kinda like a Hollywood Effect, when they only build a fasaud which looks great but there is nothing to back it up. Reducing file size is great if you post photos and dont really want people to print them with any quality. Maybe someday soon, I to will post a photo, and have to deal with this frustration. If I have not managed to make any sense to you, Please blame it on Mother Nature. It has been long known that Women often do not understand what Men are trying to say.
:)

Lyn: The main factor that the printer will look at is the DPI (dots per inch) of the printed image. For your situation (printing a 1600x1200 pixel image at 10"x8") the DPI is only 160. Printers usually want a minimum of 200 dpi, and I aim for 300dpi usually.

The second factor is the quality of the image due to compression artifacts. When you save a JPEG, some of the image information is thrown away to save space. Therefore, if you have to submit a jpg you should not compress it much (use a high JPEG quality).

Lodol . .
"When you resized your photos did you lower your file size by eliminating information?"

Eh?? Information?

I dont know! :)

I just clicked "Resize Image" in PSP, resized to 1200 x 1600, fiddled, uploaded here and thats it.Then thought they would be ok for this firm. I have had a 'photo book' printed by them - was very sucessful, but they were smaller sized images in print.

I have printed (on photo paper) one or two of the 'rejects' as an experiment and they seem fine.

Now - if I sized back UP (as size DOES appear to matter for this outfit) what would happen?
To the . .errmmm . . . resolution ?
Thats all I really want to know :) Or once downsized is some of the information lost forever ?

You are right, I dont really understand :) Pizzas and credit cards, yes :)

*caedes - thanks :)

I think I shall just forget about canvases lol and print any I want at home on my own printer. . . runs away to investigate DPI's etc.
:)

I agree with what caedes said, and don't have much to add, other than i would recommend in the future that you edit your full sized pictures, save one for your records at the larger size so if you want to print it some day you can, and then shrink it and post it here. Essentially what you are doing by saving your best images at 1600x1200 is taking your xx mega pixel camera and cutting it down to something around 2 mega pixels. You might as well keep those pixels you have to avoid this problem in the future.

your software? ..

your camera may be spitting out a 180 dpi image (i think mine does) ... your image software should have a mechanism for changing the DPI without changing the size while doing so, this is considered BAD

The Reality of Resizing

the World-Wide-Web, that we all know and love, (*scratches at veins*) is displayed on monitors that have a 72DPI resolution .. and if you are using some sort of "save for web" menu item in your software (ala Photoshop) you are resampling your image into THAT configuration .. and for good reason, 1) display on your monitor doesn't benefit by any more, 2) from an image-theft point of view, why give them something they can print and profit from

If you have photoshop, even if it isn't your drug of choice, open it, load an image, go to the Image menu, and choose Image Size .. when the dialog box opens, notice down in the lower left corner the ..

[x] Resample Image

notice, also, the Resolution box above it, displaying a number, like [180]

as the link, provided above, suggests .. change the resolution to 300 and uncheck the [_] resample image box .. and

"you can tweak the resolution 'til the cows come home and you won't alter the image quality at all. Ever."


HERE is a list from DeviantArt .. showing image submission sizes and resulting print sizes .. the "excellent" category is calculated at 300 pixels per inch of desired ink-impregnated-paper



muster the might to master your managerie of megabytes, missy

When to I go Image/Resize in PSP (I have PS but I dont like it) it tells me on
a 6MP photo straight from the camera
Width : 2816
Height: 2112
Resolution: 72.000 Pixels/inch
Then I chose to save it to 1600x 1200 and it says the print size is 22.222 x 16.667 inches. The resolution remains the same at 72.000

Next area is Resample using - either Pixel resize, Bicubic, Bilinear, Weighted Average or Smart Size.

I have it on Pixel resize - but I dont know the difference.

I also check 'Lock aspect Ratio ' and 'Resize all Layers'. I only ever have one layer anyhow.


From reading Keiths post above I am doing it all wrong? I should be changing the DPI to 300?

Tha main reason I change the size before I start editing/messing with plugins etc is because it speeds things up considerably, but I guess I had better change my ways :)

:( I feel so dumb!

NEVER feel dumb .. until I tell you otherwise ;)

Photoshop uses a BICUBIC resample and it is well regarded by most .. try that

do you have a "resample image" [x] ... because unchecking this will allow you to alter DPI without changing the size

you only need 300 DPI when printing .. and even then, maybe just when sending it to a hoity-toity printer


also .. is your camera set to its highest quality setting (fine\ultra-fine) .. this may only adjust JPEG compression .. but it may set your DPI higher .. I dunno


even if you don't understand PS now .. maybe using it for those things that it does, that another doesn't, would benefit you .. save as a PNG or TIFF to move it to your software of choice

you can always send me Photoshop questions .. I hereby vow that I will shrug my shoulders (loudly) if I can't answer it

In PSP (its Version 8) I can resample an image with the option of "maintaining original print size"

As far as I know I have my camera set at the highest quality - its just a simple camera :)

I have tried with PS in the past but it is too complicated for me and I have become used to PSP where I know my way around. Or I thought I did - gosh I cant even resize properly !
So now I will use Bicubic resizing, I actually never even noticed there was an option until now and it has always just stayed on pixel resize. What is Smart Size?
Dont anyone even try telling me what Bicubic means :)

Thanks for the help :)
I think this is a case of the more I learn the less I know :)

LynEve - OK just for fun and giggles !
Bicubic spline interpolation

Suppose the function values f and the derivatives fx,fy and fxy are known at the four corners (0,0), (1,0), (0,1), and (1,1) of the unit square. The interpolated surface can the be written

p(x,y) = \sum_{i=0}^3 \sum_{j=0}^3 a_{ij} x^i y^j.

The interpolation problem consists of determining the 16 coefficients aij. Matching p(x,y) with the function values yields four equations,

1. f(0,0) = p(0,0) = a00
2. f(1,0) = p(1,0) = a00 + a10 + a20 + a30
3. f(0,1) = p(0,1) = a00 + a01 + a02 + a03
4. f(1,1) = p(1,1) = \textstyle \sum_{i=0}^3 \sum_{j=0}^3 a_{ij}

Likewise, eight equations for the derivatives in the x-direction and the y-direction

1. fx(0,0) = px(0,0) = a10
2. fx(1,0) = px(1,0) = a10 + 2a20 + 3a30
3. fx(0,1) = px(0,1) = a10 + a11 + a12 + a13
4. f_x(1,1) = p_x(1,1) = \textstyle \sum_{i=1}^3 \sum_{j=0}^3 a_{ij} i
5. fy(0,0) = py(0,0) = a01
6. fy(1,0) = py(1,0) = a01 + a11 + a21 + a31
7. fy(0,1) = py(0,1) = a01 + 2a02 + 3a03
8. f_y(1,1) = p_y(1,1) = \textstyle \sum_{i=0}^3 \sum_{j=1}^3 a_{ij} j

And four equations for the cross derivative xy.

1. fxy(0,0) = pxy(0,0) = a11
2. fxy(1,0) = pxy(1,0) = a11 + 2a21 + 3a31
3. fxy(0,1) = pxy(0,1) = a11 + 2a12 + 3a13
4. f_{xy}(1,1) = p_{xy}(1,1) = \textstyle \sum_{i=1}^3 \sum_{j=1}^3 a_{ij} i j

where the expressions above have used the following identities,

p_x(x,y) = \textstyle \sum_{i=1}^3 \sum_{j=0}^3 a_{ij} i x^{i-1} y^j
p_y(x,y) = \textstyle \sum_{i=0}^3 \sum_{j=1}^3 a_{ij} x^i j y^{j-1}
p_{xy}(x,y) = \textstyle \sum_{i=1}^3 \sum_{j=1}^3 a_{ij} i x^{i-1} j y^{j-1}.

This is realy a simple copy of my current Income Tax form. I was just funnin you about its relevance to Photography. :)

*falls over in a dead faint*

I join Mimi - :)

I want to thank you all for your help - I wish I had asked sooner.
An added bonus for me is that I have ventured into PS and will be submitting the result later today.
I followed advice and worked on it at the original size and saved in PNG format. BUT is is a whopping 4.3MB - ok for me but not suitable I would think for uploading here so what do I do now?

if you want to upload here i would make a copy, and resize it to a smaller size.. ;)

LOL! at the million dollar man - gave me a giggle and thanks Keith for the info re. resizing - I had no idea!

It is sized to 1600 x 1200 - which is what I usually upload at.
Converting it to jpeg brings it down to 2.14MB but I wanted to try PNG

in photoshop's "FILE" menu, you will find "save for web" .. it will convert your PNG to 72 dpi .. it will show you the exact size in the lower left corner .. adjust JPEG quality via the controls on the right side, say 60, 65 .. adjust till you have the file size\quality you are willing to upload

when you click the save button, it will ask for a file name and destination .. so you won't be overwriting your original PNG


remember .. caedes.net resaves your upload as a jpeg whether you upload as a JPEG or PNG ... theory has it, the PNG will result in a higher quality end result .. but I scoff at them, HAH! .. silly techno-nerds

;)

I have decided to upload in jpeg format, as usual.
The PNG version was however, aready at 72 dpi at 1600x1200.
I am willing to upload any size, but I just imagined 4.3MB was stretching the limits. Is there a limit?


. . See how glibly the dpi trills off my tongue -
png . . . dpi. . . jpeg . . . 'tis like a song lol

Do you mean a limit in MG for uploading here Eve? If so, it is 10MB.

I always upload.png since I found out the the server here compresses our images so they don't take up too much server space. So if we upload in a lossless format such as png, there is less degradation of our images. *caedes says that* ... :o)

:) so my 4.3MG is fine!
Most of my previous jpegs are between 1 and 2

Well in actual fact there is no programmed in limit for file sizes. However from experience and feedback by members who do upload very large sizes it seems that you need to keep it below 10MB for it to upload successfully.

The interwebs (as Keifer would say) doesn't seem to like huge chunks of pixels being thrown around without putting them on timeout for bad behavior.

What does IrfanView do in resizing..?

What about RAW..?

I tried some of the effects in Picasa and did a save. The resultant file sizes were significantly smaller (jpegs).

Advantage(s) of *.png ?

mxvirgil, I think that Mimi answered your question (three commenters up) and until I went to png uploads I had significant loss of clarity and color.

PNG is considered a LOSSLESS compression scheme ..

JPEG is considered (and proving it every time) to be a LOSSY compression scheme



any "jpeg saver" is going to give you a 'slider' to adjust how much compression is applied .. 90 being qood Mi-Casa-Tu-Casa quality, and 30 being How long did you say you were going to be here?

well, I may have mixed my metaphors again


the point being .. if one program is "giving" you better file sizes than another, what it's really doing is, "taking" quality that you will never get back .... sometimes that is acceptable, other times, not ... investigate the position of the slider\numeric control and be sure it is at a level you can live with


irfanview does a swell job at a lot of things, including resizing, cropping, rotating (even lossless), picture in picture, text ... I have used it for years, and it's what I usually use to walk somebody through the steps of resizing their posts (back in the neolithic era of 4:3 ratios)

RAW ... is a format provided by some cameras (higher end) .. it is the uncompressed, un-post-processed DATA captured by your camera .. in fact it isn't even a picture, if that's ZEN enough for you .. with RAW format you have, at your fingertips, the ability to re-expose the image, using software designed for it, to bring out shadows, or squelch highlights

if your camera does not give you the ability to shoot in "the RAW" .. then it is probably doing a lot of things to your image that you may regret later, like sharpening, compressing, possibly other things that end in "ing"

Not that anybody cares, or anything, but .. PNG came about because the authors of the previously popular .GIF format started to make mewing noises when thinking about all of the wallets, in the pockets of the people, connected to the hands, moving the mice, to the "Save As .GIF" buttons, in various softwares

CompuServe Inc. and Unisys Corporation being the mewers with a hankering for CA$H .. ignoring Psalm 256 "Thou shalt not covet the contents of wallets in the pockets of people using something that YOU implied was gratis, by your failure to vocalize to the contrary at the beginning of said relationship .... amen


that, and .gif was only capable of 256 colors

follow this LINK .. but be warned .. I am covetous of some of your back pockets, and the vicinity surrounding it ... and may be charging fees for linkage, retroactively ..

Thanks, all... My camera (Pentax *ist DS) does allow saves in RAW format. At the risk of terminal tedium here, is there a good jumping-in program to manipulate RAW data? Any freeware???

I want to thank +Keifer for that link that he may or may not charge for down the line..yes I admitted it here in moveable print that I read the article on the files and the evolution of same and it was a real education. Thanks!!

:)PJ

EDIT: Since it's my birthday, I'll accept it as a present, right? *hands over a piece of my chocolate cake*

RE: RAW freeware

RAWSHOOTER essentials 2006 (Pixmantec) .. "was" free .. Adobe slurped them up, like so much gravy on a plate, just prior to the release of ADOBE LIGHTROOM

but .. it is listed in a google search as being at various shareware sites, like download.com .. or photo-freeware.net .. those links actually working would surprise me .. but you won't know till you try

Thanks, Keith.

Reminds me this thread...