13th December 2003, 04:34 PM
printing out photos
Anyone can help with the problem encountered below?
Recently tried printing out photos that i took with a 3mp camera with a hp deskjet 840c. (max resolution 2400dpi by 1200 dpi i think)
But somehow the pictures jus turn out pixelated especially obvious on skin tones and maybe white walls. And there's a slight greenish cast over the pictures.
Is the pixelation due to my printer not having high enough resolution?
Read somewhere bout ICC profiles, will doing something about the ICC profile help remove the greenish cast?
13th December 2003, 05:28 PM
The pixelation is probably due to your camera not having enough resolution. What size were you trying to print the photo at?
13th December 2003, 10:09 PM
oh..i was trying to print on 4R photo paper.
Btw, the dpi on inkjets is different from the dpi tat's mentioned in dye-sumblimed printers or outside professional printers? Cos its mentioned tat 300 dpi is enough?
13th December 2003, 11:27 PM
Hmmmm 4r photo paper and 3 mega pix images? Shouldn't be a problem? shouldn't be pixalated.... Are you shooting at full resolution of the camera? in other eords, the largest size (in terms of pixel) available for your camera?
For dpi on inket pixels, often the printer requires more than 1 drop of ink to achieve 1 pixel on screen as it needs to mix the colours...
And for greenish cast... what u get on your prints ans wat u see on screen is usually different, one reason is the way they handle the colour data of the images, by using the same icc profile for the printer, monitor etc, the color difference could be reduced... but to get very similar colours, you may need extra colour calibration tool...
14th December 2003, 10:19 PM
Yup yup, was shooting at the max resolution without any cropping...was jus wondering if it could be due to my printer not having enough resolution...
Regarding the ICC profile, ideally if my camera is set to sRGB profile, my monitor and printer should also be set to sRGB profile to reduce colour differences?
15th December 2003, 07:49 AM
You should have read your manual. You are way off on the resolution of your printer. The HP 840C's maximum resolution is only 600dpi. That's why your photos are pixelated. As for the greenish cast. That's a problem found in printer's that try to mix 3 colours to get black. ICC profiles are not going to solve your problem.
15th December 2003, 08:20 AM
hey thanks linse!
Originally Posted by linse
Ic...i got the resolution from some photo mode under advanced options. Didn't realise that the resolution was actually only 600dpi.
Bout the ink, 840c has a separate black ink cartridge, so don't think it mixes the 3 to get black.
15th December 2003, 06:24 PM
The separate black cartridge is only used when you print text. Only "photo" printers use their black cartridges when printing photos.
The "photo" blacks are lighter than the pure black cartridges that is used to print text. That's because most of the time, the black parts of your photos are not pure black, ie pixel value of 0.
The newer non-"photo" printers with higher resolutions do the same thing, except because the resolution is higher, they can dither the colours better to fool the eye into thinking there are more shades of colours and greys.
15th December 2003, 07:25 PM
hey thanks again linse for explaining it to me! Really didnt know bout all these photo-printers stuff before. Alright, guess i got my answer, thanks!
15th December 2003, 09:55 PM
Printing a photo using a consumer printer is a task full of hassles. You must first ensure that you are using the correct type of paper (I hope you do understand that you need to use photo paper to print photographs?) The 1200x2400dpi mode is achieveable only when photo paper is used. Another thing to note that because the screen and the printer uses different color spaces (sRGB vs CMYK), there's bound to be some mismatch of colors unless it's calibrated to each other. A photo resolution of 300 dpi is more than enough to print a picture with the HP840C.
I suspect you may be talking about noise rather than pixelation, because pixelation occurs throughout the whole picture rather than just skin tones and white walls...but then again I may be wrong. Pixelation is when details and definition is lost due to low resolution (jagged edges), whereas noise is unwanted, random pixels appearing in the picture.
As for the HP840C printer, it does use the black catridage to print true black, instead of mixing cyan, magenta and yellow, although it does quite an amaturish job for it. The greenish cast may be due to the wrong color balance set in the camera--pictures turn out greenish when taken under florescent lighting without the correct color balance.
15th December 2003, 11:45 PM
Ah Pao, I think you're right. I was misled into thinking the true resolution of the 840c is 600dpi from this hp website http://h20015.www2.hp.com/hub_search...cName=bud07462 I must admit, my last HP printer is a few generations older than the 840c.
However, sounds like it is not "true" 2400 x 1200 dpi though. HP's Color Layering Technology must be overlapping the ink droplets at 600 dpi to claim a the higher resolution, hence the need for special paper to prevent ink bleeding.
Anyway phantasia, to answer your question on why "the dpi on inkjets is different from the dpi tat's mentioned in dye-sumblimed printers or outside professional printers?"
Assuming the 840c resolution is 600 dpi for non-premium photo paper, I believe it will be inferior to the 300 dpi resolution of Fuji Frontier printers. That's because each "pixel" in a Fuji print has a wide gamut of thousands shades of colours. Whereas for inkjets, it will take a cluster of ink dots to fool the eye into think it is a particular shade of colour. That's why very few printers can beat digital prints from the lab. One of the few, the professional Epson 2200 printer needs a resolution of 2880 x 1440 and special inks to have a wider gamut of colour than Fuji's 300 dpi prints. It's a bit like why the 3 megapixel images from the Foveon sensors can match the resolution from the other 6 megapixel SLRs.
In that case, the "pixelation" which is more obvious on skin and white walls is due to inadequate colour gamut or colour depth. It is like when you try to save a photo in GIF format which only has 256 shades of colours instead of the thousands in JPEG. Or when save JPEGs under high compression ratios.
FYI, I do not plan on buying another photo printer as the cost of the printer, prints, ink and paper will never be cheaper than the 30 cents I currently pay for 4R prints. Larger prints will be cheaper, but have you seen the prices of A3 photo printers?
16th December 2003, 10:27 AM