problems sizing pics

[galanthus]

Hi guys, I am v v desperate

I've joined a stock site and completely understand the thumbnail-type prints they need, however, I'm having a problem sorting the originals re size They are asking for a dpi of 300, they don't state per inch or per cm so I'm assuming per inch. However, as soon as I do this, my files are coming up as big as w 16200 x H 10800 This is enormous and I fear far too big. Can anyone help me choose what is possibly a fairly standard size for the pics ? I know their different shapes etc, however, a rough idea would be great. Am completely new to the stock site thing any help wld make me happy

[eeyore]

Originally Posted by galanthus

Hi guys, I am v v desperate

I've joined a stock site and completely understand the thumbnail-type prints they need, however, I'm having a problem sorting the originals re size They are asking for a dpi of 300, they don't state per inch or per cm so I'm assuming per inch. However, as soon as I do this, my files are coming up as big as w 16200 x H 10800 This is enormous and I fear far too big. Can anyone help me choose what is possibly a fairly standard size for the pics ? I know their different shapes etc, however, a rough idea would be great. Am completely new to the stock site thing any help wld make me happy

DPI stands for dots per inch so that is the answer to your first question

stock sites expect the files to be large but not quite that large - I would suggest contacting your chosen site and asking what dimensions they prefer then you can set your photo editing software to these dimensions at 300dpi

many stock agencies also specify a minimum file size in megabytes and some require .tiff rather than .jpeg so it is definitely worth checking with them if the info isnt on their website

[galanthus]

Dot per inch Doh !!

thanx eeyore, they've specified a minimum of of 3000 pixels on the longest side, a mimimum of 3000x2000 overall. HOwever, they haven't given a maximum. I realise it's poss to get a request for a specific size and I could then modify the originals in cs2. I suppose I need help with a window of average sized pics for this kind of site. I think you've confirmed that some of the sizes are far too big so that helps. Oh and no meg maximum that I can see and the format is high quality jpeg.

[peterjclarke]

DPI = dots per inch. When you resize an in Photoshop for example you change the DPI to 300 (green circle) then in the width box (red) you type in the size e.g. 29.7cm for A4. It will obvoiusly be larger for an agency. The important bit is the resampling. I guess you are mabe not using Photoshop and whatever software you are using is resampling the image differently. An image library usually wants the full size image from a RAW file so it is best to do this in your RAW converter. My D200 it would be 3872 pixels x 2592 pixels at 300 Dpi or 32.78cm x 21.95 cm at 300Dpi.

If you are interpolating an image to a larger size this should be done using Photoshop's 'bicubic smoother' option. If reducing the size use 'bicubic sharper'.



If you are still not sure how to do this then either PM me or you can give me a call. My number is on my website Outward Vision

[mh68]

Surely the figure of 300dpi is meaningless unless related to a print size
Eg, a 10x8 print at 300 dpi would be 3000px by 2400px, whereas a 6x4 print would be 1800px by 1200px.Both are 300dpi but the actual image size in pixels is dependant on what size its going to be printed at in inches.
If the agency has specified a min image size of 3000x2000 pixels I`d go off that,and if someone asks for an image at 300dpi for a large size print, interpolate the image to the required size upon request as you mentioned.
There is a program called "genuine fractals"(just google it for info) which a lot of pro`s apparently use, which is said to give much better results than Photoshop when upsizing.If you ended up getting plenty of requests for your images it may be worth considering buying a copy.

Mark H

[Paul mabbott]

No dpi is the density/size of pixels - equivalent of grain size on a film camera. The higher the dpi the more detail is captured. Imagine going down to 10 dpi - you would have very poor definition!

Your argument applies to a projected tranparency - increase the size of the image and decrease the definition but it doesn't apply to digital images.

Originally Posted by mh68

Surely the figure of 300dpi is meaningless unless related to a print size
Eg, a 10x8 print at 300 dpi would be 3000px by 2400px, whereas a 6x4 print would be 1800px by 1200px.Both are 300dpi but the actual image size in pixels is dependant on what size its going to be printed at in inches.
If the agency has specified a min image size of 3000x2000 pixels I`d go off that,and if someone asks for an image at 300dpi for a large size print, interpolate the image to the required size upon request as you mentioned.
There is a program called "genuine fractals"(just google it for info) which a lot of pro`s apparently use, which is said to give much better results than Photoshop when upsizing.If you ended up getting plenty of requests for your images it may be worth considering buying a copy.

Mark H

[mh68]

DPI= dots per inch.A term used to define print quality. In the case of digital images dot=pixel, so really PPI (pixels per inch) would be a more accurate term to use,but DPI is the most often used. The DPI setting in relation to a specific digital image size determines what size (in inches) that image will print. Similarly, the DPI in relation to a specific print size(in inches) determines how many pixels on the X and Y axis an image must be to make that resolution.
To resize an image to a specific DPI setting a print size is required.

Mark H

[RichBrew]

300 dpi is the standard for commercial offset printing. All the work I print is at that resolution, although occasionally I see 'low res' images incorporated in layouts (which, incidentally, look dreadful).
Stock agencies require 300dpi so they can supply clients with images that will look sharp on various paper stocks used in the printing industry. Anything above 300 is deemed to be un-necessary, as the human eye has difficulty in resolving any more detail at normal viewing distances.

RichBrew

[jennyb]

Your images come out of the camera at a fixed pixel size (mine are 3888 x 2592 = 10MP). Inches/cm don't mean anything until you come to print them.

If I print them at 300dpi (or ppi as Mark says) the size would be 13" x 8.6".

If I print them at 600dpi the size would be 6.5" x 4.3".

I believe some cameras have different pixel sizes, but taking a simplistic view, I think my logic is correct?

Jenny

[mh68]

I`m not sure about varying pixel sizes between cameras,its not something i`ve seen mentioned anywhere, but the rest is spot on Jenny

Mark H

[jennyb]

I am sure I read somewhere that some cameras have smaller pixels or pixels closer together - maybe I dreamt it! My brain is suffering from information overload.

Anyway, I feel happier working in pixels because that is the base unit of a digital photograph. Inches/cm are fairly meaningless unless you want to print them.

Jenny

[galanthus]

Thanx v much guys . Very complicated stuff though isn't it ? Think I may need to sit down and analyse replies whilst referring the site. If I eva get a request to buy I'm hoping they'll specify the size they want and I can then just make sure it's 300 dpi. Until then I'll keep studying it. thanx again, you are all very fab

[peterjclarke]

Originally Posted by jennyb

I am sure I read somewhere that some cameras have smaller pixels or pixels closer together - maybe I dreamt it! My brain is suffering from information overload.

Anyway, I feel happier working in pixels because that is the base unit of a digital photograph. Inches/cm are fairly meaningless unless you want to print them.

Jenny

Your correct Jenny! manifacturers do have different pixel sizes.

[Bub-les]

Check this out it might help
All About Digital Photos

[eeyore]

Originally Posted by galanthus

Thanx v much guys . Very complicated stuff though isn't it ? Think I may need to sit down and analyse replies whilst referring the site. If I eva get a request to buy I'm hoping they'll specify the size they want and I can then just make sure it's 300 dpi. Until then I'll keep studying it. thanx again, you are all very fab

i'd suggest that if they have said 3000 x 2000 at 300 dpi is the minimum you give them arround that or a tad over ( thats a 6 megapixel image so the out put from most modern dslrs will be slightly higher)

also be aware that these dimensions are a 3:2 ratio - some cameras output a 4:3 ratio so be careful with the resize , making sure that the constrain proportions box is ticked.

I'd tend to suspect that the reason yours are ending up massive is that your camera is outputting at either 72 or 180 dpi and photoshop is changing just the dpi but keeping the pixels constant by interpolating where as you want it to reduce the dimensions proportionally as it increases dpi - to do this ensure that the resample image and interpolation boxes are unticked, when resizing.

btw i would seriously advise anyone against using interpolation to increase image size if you are selling your image files comercially because you are essentially instructing photoshop to invent data by inserting pixels inbetween the "real" ones and to guess what colour these should be by comparison with surrounding pixels - this is fine for home use or if you are printing them yourself ( tho it is best done in 10% steps) , but for comercial sale it is best to sell your image unadulterated so that the client can use whatever form of interpolation they need at their end.

this also applies to post proccessing generally which should be kept to a minimum - by all means sort out exposure, white balance etc in a raw converter and retouch any dust spots , but keep sharpening , levels, saturation etc to a bare minimum as most agencies wont touch images that have histograms that resemble fence railings.

[mh68]

What about the interpolation software I mentioned earlier Pete (genuine fractals)? would you advise against using this too for "sale" shots?
I vaguely recall Andy Rouse mentioning it somewhere...

Mark H

[eeyore]

Originally Posted by mh68

What about the interpolation software I mentioned earlier Pete (genuine fractals)? would you advise against using this too for "sale" shots?
I vaguely recall Andy Rouse mentioning it somewhere...

Mark H

if you must interpolate (ie to get to a minimum size) then genuine fractals is probably the way to go - however in my experience so long as your image meets the minimum required size it is better to leave interpolation and indeed most post processing to the client or agency as they will have specialists with more powerful computers and software to do the job.

note that i'm talking about selling image files here - if you are providing images to private clients (e.g weddings) then you would be expected to do all the necessary post processing even if you are providing a cd, and obviously if you are selling prints interpolating may well be necessary to get to bigger file sizes.

for the latter GF is the pros weapon of choice (mr rouse does indeed use it) tho others get excellent results by using CS2 in small increments.

[mh68]

Thanks mate. Although i suspect it`ll be quite a while yet (if ever) before i even contemplate selling anything its handy info to know

Mark H

[galanthus]

Originally Posted by Bub-les

Check this out it might help
All About Digital Photos

Thanks very very much for this link, it answered a very basic question for me, I've been leaving the resampling box ticked while trying to convert to 300dpi, this was making them huge Now they are the same size as before but with the 300dpi. To top it all, I've submitted 20 odd images to the site and 9 have been rated outstanding I am sooooo happy Will do lots more reading around the whole printing thing asap methinks.

thanks very much mateys for all the info. I love this place

[pressld2]

Originally Posted by galanthus

To top it all, I've submitted 20 odd images to the site and 9 have been rated outstanding

That's excellent Galanthus - way to go! They say that approx 5% of submissions receive this rating so you're way above average.

Originally Posted by eeyore

btw i would seriously advise anyone against using interpolation to increase image size if you are selling your image files comercially

That's good advice Pete, and some stock agencies specifically state that images should not be interpolated, e.g. RSPB Images. I looked into submitting to them but can't with my current camera. They ask prospective photographers to submit a maximum of 10 images which must be uninterpolated 8-bit tiffs with a file size in excess of 25Mb. An uninterpolated 8-bit tiff from a 6 megapixel camera like my D70 is just under 18Mb.

Your advice on interpolating in 10% increments is interesting too. I've only ever reduced image size ("smallerized" as my son calls it ), never increased, so I wouldn't have known that.

Dave P.