resizing pictures without losing details

Hi,

this problem has been bugging me for a moment now, I have been taking some studio shots with my canon 400D in JPG Large. So the resolution of the picture is about 3k x 2k

what i normally do is i
1) edit a lil in lightroom
2) use DPP to batch resize cos i find it easier
3) open photoshop to do some watermarking

but what i notice here is once i have it in photoshop i lose quite a significant amount of details,..especially when i zoom in at the eyes. Before this the lashes are very sharp but after all the resizing..it seems like the pixels are alot more obvious.

so i thought it was due to fact that i used too many softwares to resize my pics. I then did the following step

1) open photoshop cs2
2) edit > image size > to 1024 x 683
3) under resample image select "bicubic sharper" (was searhing around google n was told this would be the best way to resize n maintain picture quality)

this seems to be better..but im still not quite happy with it. I see alot of people resize their pictures but its amazingly sharp but not mine.could it be my base picture that was the problem?
or should i go back to using bilinear when resizing, in which i do find it not as good as bicubic sharper.

at 1 point in time i also had a doubt that maybe my picture was in jpg and the DPI was at 72...n that could be the culprit,but after reading this thread
https://photography-on-the.net …/showthread.php​?p=3740438

it seems that dpi dont really matter. but how come most printers would want me to send them a 300dpi pictures?

and what would be the main factor my pics arent turning up as sharp as the pictures? lets say i would to print 8R or 12R

thanks i do hope my questions could be answered.
tytons

I'd say after the resize and all, apply a bit of UnSharp Mask. That seems to solve most issues, anyway, though, ymmv.

tytons wrote in post #6541545
it seems that dpi dont really matter. but how come most printers would want me to send them a 300dpi pictures?

offset lytho is different to photographic printing from your inkjet or your lab..

It’s the nature of the beast. Think about it for a minute. You are taking a pic which is 3888 by 2592 or 10,077,696 pixels and scaling it to fit an image 1024 by 683 or 699,392. You threw away 9,378,304 pixels of data, or another way of thinking about it, you have chosen one pixel to represent 10 pixels in the original. Your going to loose detail as 90% of the original data is gone. You can sharpen and pull some other tricks to make it look better but data is data and when it’s not there, you’re not going to see it.

@gjl711
u got a good point there. so i guess its either sharpening the picture or if i do wan to have something tightly framed i should just cropped. right?

ok from what i read, in photoshop it actually takes out all the pixels and reassembles them or something when we resize.

how bout this mysterious DPI.

i have a pic 3k x 2k res with 72dpi

i resize it to 1024 x 683 300 dpi (as per requested by whoever wants it)
does this this image actually have a better quality in terms of detail? from 72 -> 300...where the extra pixels from from? i know our naked eye really cannot see or tell..but in terms of printing ..lets say a 12R pic..or 8R ..does it make a diff?

The dpi only affects the print size, although you can view it at this size in Photoshop, but is more accurately ppi (pixels per inch). Viewed on the Web or other computer viewer, the pixel dimensions are what matter.

Dpi is irrelevant. It's the actual number of pixels that counts.

René Damkot wrote in post #6542508
Dpi is irrelevant. It's the actual number of pixels that counts.

dun get you on this...isnt dpi the number of pixels? "dots per inch"?

so i need to open up photoshop n look for ppi?sorry if i have to ask a lil more in detail cos im at work and i dont have photoshop here.

so whats the largest size i could print with a 3888 x 2592 72dpi picture?

tonylong wrote in post #6542477
The dpi only affects the print size, although you can view it at this size in Photoshop, but is more accurately ppi (pixels per inch). Viewed on the Web or other computer viewer, the pixel dimensions are what matter.

René Damkot wrote in post #6542508
Dpi is irrelevant. It's the actual number of pixels that counts.

I should clarify what I was referring to in my statement that ppi "only affects print size":

You can resize to a specific print size with a specific ppi, and in some cases, such as some external labs, a specific ppi, such as 300, is asked for. This is also a consideration for very large prints when you want to, for instance, resize an image to a specific physical measurement and then sharpen it before pinting -- you resize and resample to your required dimensions, i.e. 20"x30" at 300 ppi, then sharpen the result viewing the pic at the desired size.

tytons wrote in post #6542580
so whats the largest size i could print with a 3888 x 2592 72dpi picture?

A 3888x2592 image, at 72 PPI, will create a 54" by 36" image. You simply divide the number of pixels by the PPI to get the number of inches.

If you set it to 300 PPI, you will have about a 13" x 8.6" image.

The ONLY thing that changing the PPI value does is change how large the printed image is. It doesn't change quality. It doesn't change how it looks on the computer screen. It simply tells the printer how large each pixel in the image should be on the paper. If you set it to 1 PPI, you can print off that image at 324 feet by 216 feet, as big as a football field! At that size, each pixel in the image will be a 1 square inch block on the printed image.

ahh...i think i got the whole picture now..hmm so having larger ppi means the pic is actually..uglier...due to the fact tat the pixels is actually larger.

can i sum up that dpi is the reverse of ppi?

having more dpi maybe means having more dots in 1 inch.

but having more ppi means tat theres less pixels in an inch..so basically these 2 are the opposite of each other..

more dpi = maybe nicer pic
less ppi = nicer pic

No, they express the same idea, but in different contexts.

DPI = Dots Per Inch = a printing term that tells how many dots of ink are in one inch. The more dots, the finer detail you get. Notice that these are just "dots" or blobs of ink. It has nothing to say about where the image comes from, only how many blobs per inch that the printer will put on the paper.

PPI = Pixels Per Inch = a digital imaging term that tells you how large or small each pixel in a digital image will be on the printed paper. It has nothing to say about how to make up that pixel on the paper, just how large it will be.

The issue that confuses people is that the two can be uncoupled in printing digital images, or they can be the same. The DPI setting determined by your printer: how many dots the inkjet nozzle can put in one inch. No matter what you print, for example, your printer may print at 600 DPI. The PPI setting is what you control yourself. If you set the PPI on your image equal to the DPI that your printer puts out, that means that your printer will put one blob of ink on the page for every pixel in your image. If your printer prints at 600 DPI, and you set your image to 300 PPI, that means that your printer will print FOUR (2*2) blobs of ink for every pixel in your image. If you set it to 60 PPI on that image, your printer will print a HUNDRED (10*10) blobs of ink for every pixel in your image (and thus the pixels will look much larger).

dpi, ppi and pixel size are all different things.

Actual pixels are size less. They are just units of information and their size is totally dependent on the device which will display them. When your thinking about an image and the information it contains, this is the only number that matters. So you're 3888 by 2592 picture contains 10,077,696 pixels.

DPI and PPI are related but each has a slightly different function. DPI is the dot per inch that the printer is going to be printing. It can be different the the resolution of the photo. For instance, you printer is capable of printing 300 dots per inch. That's the printers resolution. PPI is how many of your images pixels will be printed per inch. They can be the same as the printers DPI or it can be different.

Think of 72dpi as "tennis ball sized pixels" and of 300dpi as "golfball sized pixels":
With the same amount of pixels, you'll cover a bigger area with the tennis balls, but the pixels are larger.

So you might see individual pixels if you view from up close.

The good thing is, you don't view huge pictures up close. That's why a billboard image usually does fien at something like 30 or even 10 dpi.

i think i roughly got it...
ok since Dpi is close to insignificant...why do nikon camera's take jpg in 300DPI? whereas canon is only 72dpi.

is there such a reason for such thing? since what matters most when we're resizing is the ppi when printing. i got confused about these things because when i ask ppl how come my picture quality seems to degrade and all..they would usually tell me increase your dpi..to 100 atleast or something..which then i did but sense no difference..instead always wonder..if ur increasing 72-100..where on earth is the extra data coming from(dots in this case)...

whereas if it was like a picture from the nikon camera..it would make a lil more sense cos ur reducing from 300 to 100dpi.but after reading through your comments it seems tat its the number of pixels that matters (height x width)

im sorry if im making you guys lose your patience...takes a while for me to gasp this confusing issue