PhotoFiltre

Le forum officiel de PhotoFiltre
Nous sommes le 16 Déc 2018 18:24

Heures au format UTC + 1 heure




Poster un nouveau sujet Répondre au sujet  [ 5 messages ] 
Auteur Message
 Sujet du message: DPI and pixels
MessagePosté: 08 Aoû 2012 4:57 
Hors ligne
Régulier
Régulier(ère)|Régulier|Régulière

Inscription: 26 Aoû 2010 0:15
Messages: 119
Sexe: Masculin
Version de PhotoFiltre: 7.0.0
Système d'exploitation: windows xp sp2
Processeur: Intel p4 2800mhz
Mémoire RAM: 1.5 gig
Hi all,
I'm really confused. My sister has asked me to edit a picture for her of an old photograph, that she had scanned at the local photo shop in Vancouver. After editing it, I decided that in order to make it a reasonable size for emailing, I would reduce it from 1200dpi to 300dpi, but there was hardly any difference in file size, and when I blow up both pictures, on my computer screen, I can't see any difference in image quality. Am I missing something?
Thanks,
......john


Haut
 Profil  
 
 Sujet du message: Re: DPI and pixels
MessagePosté: 08 Aoû 2012 10:15 
Hors ligne
Modérateur Global
Modérateur(trice) Global(e)|Modérateur Global|Modératrice Globale
Avatar de l’utilisateur

Inscription: 02 Fév 2005 9:35
Messages: 13397
Localisation: 54
Sexe: Masculin
Version de PhotoFiltre: PF6 + 7 + Studio
Système d'exploitation: Xp + W10
Hi Shinnen,

the resolution in DPI is only useful for scanning, printing, or displaing on a screen with some particular applications.

You only need to watch to the physical size of the numeric image which is the size in pixels.

The physical size of a printed photography is its size in inch or centimeters.
The dpi is only used to convert a physical size of numeric image in its physical size to be printed for exemple. (or inverse for scanning)
But the printing window of PhotoFiltre does that easily for you.

The size in pixels of an image is the first element accountable of the "weight" of a picture file,
- secondly : the number of colours inside
- thirdly : the compression level you chose to convert a numeric image as a numeric file.

For mailing an image and illustrate a topic, a size of 800 x 600 pixels is generaly a suffisant weight / quality compromise.
If a photography is transmitted intend to be printed in a classic format 6 x 4 inches, the classic scrreen format is suffisant : 1280 x 853 pixels
but you can go to a HD format in 1080 pixels high.

In PhotoFiltre, to reduce the size of the numeric image according with the resolution :
you need in the Image size window to switch the pixels unit to inch or centimeters and then the resolution is used for reduce the physical size.
But this operation reduce also the quality of the image. Try and test on some copies.
If the unit is pixel, the resolution is only used by applications which are able to display a future printing size, and that is without any quality lost,
but generaly it is useless.

_________________
Bien plus facile avec PhotoFiltre. Cordialement.
. . Image . . Image


Haut
 Profil  
 
 Sujet du message: Re: DPI and pixels
MessagePosté: 08 Aoû 2012 16:23 
Hors ligne
Régulier
Régulier(ère)|Régulier|Régulière

Inscription: 26 Aoû 2010 0:15
Messages: 119
Sexe: Masculin
Version de PhotoFiltre: 7.0.0
Système d'exploitation: windows xp sp2
Processeur: Intel p4 2800mhz
Mémoire RAM: 1.5 gig
Hi Tom,
I never print picture's here. I'm going to sent this to my sister, and she is going to have an image made from it 5x7 or 4x6 ...... I don't know. When I change the resolution from 1200dpi to 300dpi, does this affect the clarity of the printed picture? If so, can I change 300dpi back to 1200dpi? Right now the image is 4200x6400 pixels....... about 8.5 mbs. I have to ask these questions, because my sister is even dopier than I. She is unable to transfer the picture I send her by e-mail to a disk or flash card, so I have to send it to her in one of those forms, so I want to get it right before I do that.
Thanks for your patience.
.... john


Haut
 Profil  
 
 Sujet du message: Re: DPI and pixels
MessagePosté: 01 Oct 2012 14:49 
Hors ligne
Modérateur Global
Modérateur(trice) Global(e)|Modérateur Global|Modératrice Globale
Avatar de l’utilisateur

Inscription: 02 Fév 2005 9:35
Messages: 13397
Localisation: 54
Sexe: Masculin
Version de PhotoFiltre: PF6 + 7 + Studio
Système d'exploitation: Xp + W10
Hi Shinnen,

the main informations of the matter were in my last post and i thought they need some time to be red and practised
before to be assimilated. At first, It is not obvious for anybody, and i have had also some wrong received ideas on the question.

Now you can almost forget the resolution value and watch to the pixels size of the destination image.

Keep always somewhere the original image in the native size.

  • For a gift copy use an usual screen size (1280 x 960 pixels or a little more).
  • For illustrate a conversation in an email, a 800 x 600 pixels copy is suffisant.
  • For a printing on any hardware or online services use a copy of the original size image and choose your paper size.
    All the good softwares do what is needed to give you the size you have choosen.
Yes for the clarity, when you have reduced the size of an image, you can do menu Filter/Sharpen/Sharpen edges.
And if it's too much : menu Edit/Fade or Shift + Ctrl + Z

_________________
Bien plus facile avec PhotoFiltre. Cordialement.
. . Image . . Image


Haut
 Profil  
 
 Sujet du message: Re: DPI and pixels
MessagePosté: 02 Oct 2012 15:59 
Hors ligne
Régulier
Régulier(ère)|Régulier|Régulière

Inscription: 26 Aoû 2010 0:15
Messages: 119
Sexe: Masculin
Version de PhotoFiltre: 7.0.0
Système d'exploitation: windows xp sp2
Processeur: Intel p4 2800mhz
Mémoire RAM: 1.5 gig
Hi Tom,
Thanks again for your help.
.... john


Haut
 Profil  
 
Afficher les messages postés depuis:  Trier par  
Poster un nouveau sujet Répondre au sujet  [ 5 messages ] 

Heures au format UTC + 1 heure


Qui est en ligne

Utilisateurs parcourant ce forum: Aucun utilisateur enregistré et 1 invité


Vous ne pouvez pas poster de nouveaux sujets
Vous ne pouvez pas répondre aux sujets
Vous ne pouvez pas éditer vos messages
Vous ne pouvez pas supprimer vos messages

Rechercher:
Aller à:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Traduction par: phpBB-fr.com